Photosensitivity

Related Terms

Actinic prurigo, allergic, allergic reaction, allergic response, antihistamines, beta-carotene, hives, hydrocortisone, Ig, IgE, immune, immune defense system, immune reaction, immune response, immune system, immunoglobulin, immunoglobulin E, rash, sensitivity to light, photoallergic, photoallergic eruption, photodermatology, photo test, photo testing, PMLE, polymorphous light eruption, PUVA, sensitized, sensitization, skin plaques, skin rash, solar hives, solar urticaria, sunblock, sunburn, ultraviolet light, UV, UV light.

Background

Sun allergy, also called photosensitivity, occurs when the body's immune system overreacts to sunlight exposure. Patients who are allergic to sunlight typically develop an itchy red rash on areas of the skin that were exposed to light. In rare cases, some patients may develop hives or blisters.
Patients of all skin tones (from light to dark) can develop skin allergies. It remains unclear exactly why sensitive patients develop this reaction. It is believed that light causes changes in parts of the skin that are exposed to the sun. The body then identifies this sun-altered skin as a foreign substance, the same way it would bacteria or viruses. This triggers the immune system to launch an attack, which produces symptoms of an allergic reaction.
In some cases, chemicals from products that are applied to the skin (like lotion or perfume) or chemicals in oral medications (like antibiotics or diuretics) may lead to an allergic reaction to sun exposure.
Photosensitivity is not the same as sunburn. Photosensitivity occurs when the body's immune system reacts to light. Sunburn, on the other hand, occurs when the amount of sun or ultraviolet light exposure exceeds the ability of the body's pigment called melanin to protect the skin.
Some of the most common types of sun allergies include polymorphous light eruption (PMLE), actinic prurigo (hereditary PMLE), photoallergic eruption, and solar urticaria (hives).
In some patients, the sensitivity to light gradually declines with subsequent exposures. If a cream, ointment, perfume, or other chemical is causing a sun allergy, patients should discontinue using the product and symptoms will subside. If a medication is causing symptoms, a healthcare professional may recommend discontinuing the medication or altering the dose. Once the offending chemical or medication is discontinued, the patient will not have allergic reactions to sunlight. Some patients may need to minimize their exposure to sunlight, but treatments, including antihistamines, hydrocortisone, phototherapy, and/or PUVA, may help relieve allergic symptoms.

Author information

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

American Academy of Dermatology. .
DermNet NZ. .
Fesq H, Ring J, Abeck D. Management of polymorphous light eruption: clinical course, pathogenesis, diagnosis and intervention. Am J Clin Dermatol. 2003;4(6):399-406. .
Naleway AL, Greenlee RT, Melski JW. Characteristics of diagnosed polymorphous light eruption. Photodermatol Photoimmunol Photomed. 2006 Aug;22(4):205-7. .
National Cancer Institute. .
National Institute of Arthritis and Musculoskeletal and Skin Diseases. .
Natural Standard: The Authority on Integrative Medicine. .
Schauder S. [Solar urticaria]. [Article in German]. Hautarzt. 2003 Oct;54(10):952-8. .
Sun Safety Alliance. .

Causes

Sunlight is made up of ultraviolet A (UVA) and ultraviolet B (UVB) rays. Individuals may be allergic to one type of ultraviolet ray or both.
Researchers suspect that the ultraviolet rays that are present in sunlight cause changes in parts of the skin that are exposed to the sun. The immune system of allergic patients mistakenly identifies this sun-altered skin as a foreign substance like bacteria or a virus. This triggers the immune system to launch an attack, which produces symptoms of an allergic reaction.
In some cases, chemicals from products that are applied to the skin (lotion or perfume) or chemicals in oral medications or herbs (St. John's wort) may lead to an allergic reaction after sun exposure. The sunlight interacts with the chemical, and the body's immune cells recognize it as a foreign invader. Once the cells begin an attack, symptoms of an allergic reaction develop.

Symptoms

General: The duration of exposure to sunlight that causes an allergic reaction varies among patients. Also, allergic reactions may develop more rapidly if the patient is exposed to higher strengths of sunlight or if they are exposed to sunlight for longer periods of time.
Actinic prurigo (hereditary PMLE): Symptoms of actinic prurigo (hereditary PMLE) are similar to those of polymorphous light eruption (PMLE), but they are usually concentrated on the face, especially around the lips. Symptoms may be more severe than classic PMLE. Also, patients with this type of allergy usually begin experiencing symptoms during childhood or early adolescence.
Photoallergic eruption: Symptoms vary depending on the patient's underlying medical condition and specific medication he/she is taking. Symptoms of photoallergic eruption may not develop until one to two days after sun exposure. Common symptoms include red itchy rash and/or small blisters on the skin. The skin reaction may develop on areas of the skin that were covered with clothing.
Polymorphous light eruption (PMLE): Symptoms of polymorphous light eruption (PMLE) usually develop within two hours after sun exposure. Common symptoms include an itchy or burning rash on exposed areas of skin, especially the arms, legs, upper chest, and neck. Some patients may also experience chills, headache, nausea, and general feeling of discomfort. There are have also been rare reports of fluid-filled blisters, bleeding under the skin, and red, flat raised bumps (called plaques) on the skin. Symptoms generally resolve in 2-3 days if further sun exposure is avoided.
The duration, intensity, and type of symptoms vary among patients. Symptoms generally resolve after the offending chemical is discontinued.
Solar urticaria (hives): Hives usually develop on exposed areas of skin within minutes. Hives are red, raised itchy welts (wheals) of varying sizes on the surface of the skin. Hives begin to resolve after 30 minutes to two hours.

Diagnosis

General: A photo test is used to diagnose sun allergies. If a patient tests positive for sun allergies and has symptoms of photoallergic eruption, a healthcare provider may ask detailed questions about medications and products that the patient applies to the skin. A healthcare provider may suggest that the patient discontinues certain medications or products to determine whether they are causing the allergic reaction.
Photo testing: A procedure called photo testing is the standard diagnostic tool for sun allergies. During the procedure, a small sample of the patient's skin is exposed to a measured amount of ultraviolet light. If the sampled skin develops hives or eruptions or becomes red, itchy, or swollen, a positive diagnosis is made.

Treatment

General: If a cream, ointment, perfume, etc. is causing a sun allergy, patients should discontinue using the product and symptoms will subside. If a medication is causing symptoms, a healthcare provider may recommend discontinuing the medication or altering the dose. However, if the medication cannot be discontinued or altered, a healthcare provider may recommend avoiding sun exposure until treatment is completed. Other treatments, including antihistamines, hydrocortisone, phototherapy, and/or PUVA may help relieve allergic symptoms.
Antihistamines: Oral antihistamines like diphenhydramine (Bendaryl?) have been used to treat hives and red, itchy skin. This medication is used most often in patients with polymorphous light eruption (PMLE) or solar urticaria.
Beta-carotene: Supplementation with oral beta-carotene has been used to treat sun allergy. This treatment is used most often in patients who have PMLE or actinic prurigo (hereditary PMLE). In sun-sensitive individuals, 25 milligrams of beta-carotene has been taken by mouth daily.
Hydrocortisone: Hydrocortisone cream has been applied to the affected area of skin to temporarily relieve itching. This medication is used most often in patients with PMLE or solar urticaria. Hydrocortisone 1% cream, which is available over-the-counter, has anti-inflammatory effects and relieves swelling and redness in addition to itching.
Phototherapy: Phototherapy, which involves gradually exposing the skin to increased levels of ultraviolet light, has also been used to treat sun allergy. This is typically used in patients who have PMLE or solar urticaria (hives). Phototherapy is performed at a healthcare provider's office. Patients are usually exposed to ultraviolet light five times per week for three weeks. Patients usually begin to develop a tolerance to sun exposure and allergic symptoms to sun exposure are reduced.
PUVA: PUVA is a combination of psoralen and ultraviolet light. PUVA may be performed if a patient is not responding to phototherapy. This is typically used in patients who have hereditary PMLE or classic PMLE. Psoralen, a compound found in many plants, makes the skin temporarily sensitive to ultraviolet light.
Sunscreen: Allergic patients who cannot avoid exposure should apply sunblock to the skin whenever they are outside. Patients should choose a sunblock with a sun protection factor (SPF) of 15 or higher. The sunblock should offer protection against both ultraviolet A (UVA) and ultraviolet B (UVB) rays. Allergic patients should also use sunblock that is formulated especially for the lips. Patients should choose lip sunblock with an SPF of 20 or more. Also, patients should look for products that are "PABA-free." PABA is a chemical that is found in many sunblocks, and it has been shown to cause irritation in sensitive patients.

Integrative therapies

Good scientific evidence:
Beta carotene: Beta-carotene is a member of the carotenoids, which are highly pigmented (red, orange, yellow), fat-soluble compounds naturally present in many fruits, grains, oil, and vegetables (green plants, carrots, sweet potatoes, squash, spinach, apricots, and green peppers). The carotenes possess antioxidant properties. Erythropoietic protoporphyria is a rare inherited genetic disorder of porphyrin-heme metabolism that has skin and systemic manifestations, including photosensitivity (painful skin sensitivity to sunlight), as well as gallstones and liver dysfunction. It is usually recognized during childhood. The over-the-counter synthetic beta-carotene product Lumitene? is U.S. Food and Drug Administration (FDA)-approved for photoprotection in this disease.
High levels of beta-carotene have been associated with the development of lung cancer in smokers. Avoid if sensitive to beta-carotene, vitamin A, or any other ingredients in beta-carotene products.
Unclear or conflicting scientific evidence:
Acupuncture: Acupuncture has been found beneficial for hives, although more research is needed to confirm these findings.
Needles must be sterile in order to avoid disease transmission. Avoid with valvular heart disease, infections, bleeding disorders or with drugs that increase the risk of bleeding (anticoagulants), medical conditions of unknown origin, neurological disorders. Avoid on areas that have received radiation therapy and during pregnancy. Use cautiously with pulmonary disease (like asthma or emphysema). Use cautiously in elderly or medically compromised patients, diabetics or with history of seizures. Avoid electroacupuncture with arrhythmia (irregular heartbeat) or in patients with pacemakers.
Agrimony: It remains unclear whether agrimony can effectively treat cutaneous disorders and rashes. Further research is needed to determine if agrimony is safe and effective.
Avoid if allergic or hypersensitive to agrimony or its related species. When used as recommended, agrimony is considered to be safe. Avoid with bleeding disorders, kidney or liver disease, or diabetes. Use cautiously with drugs that lower blood pressure.
Beta carotene: Beta-carotene has been studied for polymorphous light eruption (PLE) as well as UV-induced erythema in individuals sensitive to sun exposure. Additional research is needed to make a conclusion.
High levels of beta-carotene have been associated with the development of lung cancer in smokers. Avoid if sensitive to beta-carotene, vitamin A or any other ingredients in beta-carotene products.
Bromelain: Bromelain has been shown to decrease inflammation, regulate the immune system, and have antiviral effects and may help treat skin rash.
Avoid if allergic to bromelain, pineapple, honeybee, venom, latex, birch pollen, carrots, celery, fennel, cypress pollen, grass pollen, papain, rye flour, wheat flour, or members of the Bromeliaceaefamily. Use cautiously with a history of bleeding disorders, stomach ulcers, or heart, liver, or kidney disease. Use caution before dental or surgical procedures or while driving or operating machinery. Avoid if pregnant or breastfeeding.
Butterbur: Preliminary research suggests that butterbur may not suppress allergic skin disease reactions when compared to the prescription drug fexofenadine (Allegra?), which does suppress these reactions. Additional study is needed. Use caution if allergic or sensitive to Petasites hybridus or other plants from the Asteraceae/Compositae family (like ragweed, marigolds, daisies and chrysanthemums). Raw, unprocessed butterbur plant should not be eaten due to the risk of liver or kidney damage or cancer. Avoid if pregnant or breastfeeding.
Calendula: Limited early research suggests that calendula extracts may reduce skin inflammation. Human studies are lacking in this area.
Avoid if allergic to plants in the Aster/Compositae family such as ragweed, chrysanthemums, marigolds, and daisies. Use cautiously in patients taking sedatives, blood pressure medications, cholesterol medications, blood sugar-altering agents, and immunomodulators. Use cautiously with diabetes and in children. Avoid if pregnant or breastfeeding.
Chamomile: The German Commission E authorizes the use of topical chamomile for diseases of the skin. Topical chamomile preparations have traditionally been used to soothe skin inflammation. The existing human evidence shows that chamomile may be of little, if any, benefit while animal studies support its anti-inflammatory action. Additional human research is needed in this area.
Avoid if allergic to chamomile. Anaphylaxis, throat swelling, skin allergic reactions and shortness of breath have been reported. Chamomile eyewash may cause allergic conjunctivitis (pinkeye). Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Use cautiously if driving or operating machinery. Avoid if pregnant or breastfeeding.
Green tea: There is limited animal and human study of green tea as an agent for photoprotection from ultraviolet light skin injury. Some study results conflict. Comparisons have not been made with well-established forms of sun protection such as ultraviolet protective sunscreen. Thus, the effects of green tea on skin damage caused by the sun remain unclear.
Green tea contains caffeine, which is a stimulant. Avoid if allergic or hypersensitive to caffeine or tannins. Use cautiously with diabetes or liver disease.
Lutein: Lutein is found in high levels in foods such as green vegetables, egg yolk, kiwi fruit, grapes, orange juice, zucchini, squash, and corn. For some commercially available supplements, lutein is extracted from marigold petals.Numerous laboratory studies have shown the antioxidant effect of lutein. More information is needed before a conclusion can be made regarding the use of lutein for UV-induced erythema.
Avoid if allergic or hypersensitive to lutein or zeaxanthin. Use cautiously if at risk for cardiovascular disease or cancer. Avoid if pregnant or breastfeeding.
Lycopene: High levels of lycopene are found in tomatoes and in tomato-based products. Lycopene in combination with other carotenoids, such as beta-carotene, vitamins C and E, selenium, and proanthocyanidins, may help in reducing sunburn. Selected protective effects for sun protection from UV rays have been observed in small, short-term studies. More research is needed before a firm conclusion can be drawn.
Avoid if allergic to tomatoes or to lycopene. Due to a lack of conclusive data, avoid if pregnant or breastfeeding.
Marshmallow: Marshmallow extracts have traditionally been used to treat inflammatory skin conditions. Several laboratory experiments, mostly in the 1960s, reported marshmallow to have anti-inflammatory activity but limited human study is available. Safety, dosing, and effectiveness compared to other anti-inflammatory agents have not been examined.
Historically, marshmallow is generally regarded as being safe in healthy individuals. However, since studies have not evaluated the safety of marshmallow, proper doses and duration in humans are not known. Allergic reactions may occur. There is not enough scientific evidence to support the safe use of marshmallow during pregnancy or breastfeeding.
Onion: Early study suggests that application of an alcoholic onion extract on the skin may reduce allergic responses, such as wheals (hives) and flares. More research is needed.
Avoid if allergic or hypersensitive to onion (Allium cepa), its constituents, or members of the Lilaceae family. Use cautiously with hematologic (blood) disorders, diabetes, hypoglycemia (low blood sugar), and hypotension (low blood pressure). Use cautiously if taking anticoagulants or antiplatelets (blood thinners). Avoid medicinal doses if pregnant or breastfeeding.
Para-aminobenzoic acid: PABA (para-aminobenzoic acid) is most well known for its topical use as a component of sunscreen products. Further studies may help to explain PABA's mechanism of action for photoprotection; however, its use as a component of sunscreens has diminished recently due to the reportedly high frequency of allergic reactions and cross-sensitivity with other medications. Additional investigations are also needed regarding the use of PABA for inflammatory skin disorders in general.
Avoid with known hypersensitivity to PABA or its derivatives. Discontinue use if rash, nausea, or anorexia occurs. Avoid oral use in children and pregnant or nursing women. Use cautiously in patients with renal or liver disease. PABA should not be given concurrently with sulfonamides. Use cautiously in patients with bleeding disorders or taking anticoagulants. Use cautiously in patients with diabetes or hypoglycemia.
Polypodium leucotomos extract and anapsos: Early study has shown that polypodium may help to prevent skin damage caused by the sun such as sunburn, skin aging, and skin cancers resulting from uncontrolled overexposure to solar UV radiation (UVA and UVB). Further research is needed to confirm these results.
Use cautiously with heart disease or with blood pressure drugs. Avoid operating any heavy machinery when taking polypodium. Avoid if allergic to ferns (in the family Polypodiaceae) or if pregnant or breastfeeding.
Pomegranate: Taking ellagic acid-rich pomegranate extract by mouth may reduce damage to the skin, such as sunburn, caused by exposure to UV rays. Additional studies are needed.
Avoid if allergic or hypersensitive to pomegranate. Avoid with diarrhea or high or low blood pressure. Avoid taking pomegranate fruit husk with oil or fats to treat parasites. Pomegranate root/stem bark should only be used under the supervision of a qualified healthcare professional. Use cautiously with liver damage or liver disease. Pomegranate supplementation may be unsafe during pregnancy when taken by mouth. The bark, root, and fruit rind may cause menstruation or uterine contractions. Avoid if breastfeeding due to a lack of scientific data.
Pycnogenol: Pycnogenol?, taken by mouth, may reduce sunburn caused by solar ultraviolet light. Further study is needed before a recommendation can be made.
Avoid if allergic/hypersensitive to pycnogenol, its components, or members of the Pinaceae family. Use cautiously with diabetes, hypoglycemia, or bleeding disorders. Use cautiously if taking hypolipidemics, medications that may increase the risk of bleeding, hypertensive medications, or immune stimulating or inhibiting drugs. Avoid if pregnant or breastfeeding.
Selenium: Sunburn prevention was initially observed in preliminary research using selenium supplementation and other antioxidants, although there is some evidence of ineffectiveness.
Avoid if allergic or sensitive to products containing selenium. Avoid with history of non-melanoma skin cancer. Selenium is generally regarded as safe for pregnant or breastfeeding women. However, animal research reports that large doses of selenium may lead to birth defects.
Soy: A soy moisturizing cream may help improve signs of skin damage caused by the sun, including discoloration, blotchiness, dullness, fine lines, and overall texture. Because the cream contains other ingredients in addition to soy, more research with soy alone is needed.
Avoid if allergic to soy. Breathing problems and rash may occur in sensitive people. Soy, as a part of the regular diet, is traditionally considered to be safe during pregnancy and breastfeeding, but there is limited scientific data. The effects of high doses of soy or soy isoflavones in humans are not clear. People who experience intestinal irritation (colitis) from cow's milk may experience intestinal damage or diarrhea from soy. It is not known if soy or soy isoflavones share the same side effects as estrogens, like increased risk of blood clots. The use of soy is often discouraged in patients with hormone-sensitive cancers, such as breast, ovarian, or uterine cancer. Other hormone-sensitive conditions such as endometriosis may also be worsened. Patients taking blood-thinning drugs like warfarin should check with a doctor and pharmacist before taking soy.
Tea tree oil: Small studies show that tea tree oil applied to the skin may reduce allergic skin reactions caused by histamine-induced inflammation. Further research is needed to confirm these results.
Avoid allergic or hypersensitive to tea tree oil (Melaleuca alternifolia), any of its constituents, balsam of Peru, benzoin, colophony (rosin) tinctures, eucalyptol, or members of the Myrtle (Myrtaceae) family. Avoid taking tea tree oil by mouth. Avoid if taking antineoplastic agents. Use tea tree oil applied to the skin cautiously in patients with previous tea tree oil use. Avoid if pregnant or breastfeeding.
Thyme: Historically, thyme has been used topically for a number of inflammatory skin disorders. Results are mixed. Additional study is needed in this area.
Avoid with known allergy/hypersensitivity to members of the Lamiaceae (mint) family or to any component of thyme, or to rosemary (Rosmarinus officinalis). Avoid oral ingestion or non-diluted topical application of thyme oil due to potential toxicity. Avoid topical preparations in areas of skin breakdown or injury, or in atopic patients, due to multiple reports of contact dermatitis. Use cautiously in patients with gastrointestinal irritation or peptic ulcer disease due to anecdotal reports of gastrointestinal irritation. Use cautiously in patients with thyroid disorders due to observed anti-thyrotropic effects in animal research of the related species Thymus serpyllum. Avoid if pregnant or breastfeeding.
Vitamin C: Vitamin C and vitamin E applied to the skin may not prevent UVA-induced skin damage. Further research is needed to confirm early study findings.
Avoid if allergic or sensitive to vitamin C product ingredients. Vitamin C is generally considered safe in amounts found in foods and if taken in recommended doses. Avoid high doses of vitamin C with glucose 6-phosphate dehydrogenase deficiency, kidney disorders or stones, cirrhosis (inflammation of the liver), gout, or paroxysmal nocturnal hemoglobinuria (bleeding disorder). Vitamin C intake from food is generally considered safe if pregnant or breastfeeding.
Witch hazel: Although witch hazel has been commonly used to relieve minor skin irritation, there are few human studies evaluating its use for this purpose, especially in children. High quality human study is needed for a conclusion to be made.
Avoid if allergic or sensitive to witch hazel. Avoid if pregnant or breastfeeding. Use cautiously in people with liver or kidney disorders, diabetes, and in children.
Traditional or theoretical uses lacking sufficient evidence:
Burdock: Burdock is a plant that is native to Europe and northern Asia. The root is most often used in herbal preparations. Traditionally, burdock has been used to treat hives. However, human evidence on its safety and effectiveness for this use is currently lacking.
Avoid if allergic to burdock or other plants of the Asteraceae/Compositae family (such as ragweed, chrysanthemums, marigolds, or daisies). Avoid with a history of dehydration, diabetes, heart disease, cancer, high blood pressure, or HIV. Stop use before and immediately after surgeries or dental or diagnostic procedures with bleeding risks. Avoid if pregnant or breastfeeding.
Chamomile: Chamomile is an herb that has an apple-like smell and taste. It is commonly taken as a tea. Although chamomile has traditionally been used to treat hives, scientific evidence is lacking. Currently, human trials have not evaluated the safety or effectiveness of chamomile for this use.
Avoid if allergic to chamomile or any related plants, such as aster, chrysanthemum, mugwort, ragweed, or ragwort. Stop use two weeks before and immediately after surgery/dental/diagnostic procedures with bleeding risks. Use cautiously if driving or operating machinery. Avoid if pregnant or breastfeeding.
Detoxification therapy (cleansing): Detoxification is a broad concept that encompasses many different modalities and substances used in cleansing the body's systems and organs. Detoxification has been suggested as a possible treatment for hives. However, human evidence on its safety and effectiveness for this use is currently lacking.
In cases of illness, the various forms of detoxification should be used under professional guidance. See specific monographs for precautions and warnings associated with modalities of detoxification.
Ephedra: Ephedra is a natural stimulant. Traditionally, ephedra has been used to treat hives. However, human evidence on its safety and effectiveness for this use is currently lacking.
Even though this herb has been suggested as a potential treatment for hives, it is unsafe for humans. Serious reactions, including heart attack, stroke, seizure, and death have occurred. The U.S. Food and Drug Administration (FDA) has banned sales of ephedra dietary supplements. The FDA has collected more than 800 reports of serious toxicity, including more than 22 deaths. Avoid use in individuals younger than 18 years old. Avoid use for prolonged periods (longer than seven days) due to risk of abuse or toxicity. Discontinue use at least one week prior to major surgery or diagnostic procedures. Use cautiously with cardiovascular disease, including structural heart disease, arrhythmia, coronary artery disease, high blood pressure, cerebrovascular disease, and a history of stroke or transient ischemic attack. Use cautiously with depression, anxiety disorders, anorexia/bulimia, a history of suicidal ideation, insomnia, tremors, urinary retention, enlarged prostate, diabetes, kidney disease, glaucoma, thyroid disease, and peptic ulcer disease. Use cautiously with monoamine oxidase inhibitor (MAOI) or stimulant use. Avoid if pregnant or breastfeeding.
Kudzu: Kudzu is an herb that has been used in Chinese medicine for many years. Traditionally, kudzu has been used to treat hives. However, human evidence on its safety and effectiveness for this use is currently lacking.
No well-designed studies on the long-term effects of kudzu are available. Avoid if allergic or hypersensitive to Pueraria lobata or members of the Fabaceae/Leguminosae family. Use cautiously with blood thinners and blood pressure-lowering agents, hormones, antiarrhythmics, benzodiazepines, bisphosphonates, diabetes medications, drugs that are metabolized by the liver's cytochrome P450 enzymes, mecamylamine, neurologic agents, and methotrexate. Avoid if pregnant or breastfeeding.
Moxibustion: Moxibustion is a therapeutic method in traditional Chinese medicine, classical (five element) acupuncture, and Japanese acupuncture. During the therapy, an herb (usually mugwort) is burned above the skin or on the acupuncture points in order to introduce heat into an acupuncture point and alleviate symptoms. There is limited evidence suggesting that moxibustion may help treat hives. Additional research is needed to evaluate the safety and efficacy of moxibustion for this use.
Use cautiously over large blood vessels and thin or weak skin. Avoid with aneurysms, any kind of "heat syndrome," heart disease, convulsions, cramps, diabetic neuropathy, extreme fatigue and/or anemia, fever, or inflammatory conditions. Avoid use over allergic skin conditions, ulcerated sores, skin adhesions, or inflamed areas or organs. Do not use on contraindicated acupuncture points, the face, genitals, head, or nipples. Use cautiously in patients who have just finished exercising or taking a hot bath or shower. Use cautiously in elderly people with large vessels. Not advisable to bathe or shower for up to 24 hours after a moxibustion treatment. Avoid if pregnant or breastfeeding.
Peppermint oil: Peppermint is a flowering plant that grows throughout Europe and North America. Peppermint is usually grown for its fragrant oil. Historically, peppermint has been used to treat hives. Further research is needed to determine whether peppermint is safe and effective for this use.
Avoid if allergic or hypersensitive to peppermint or menthol. Peppermint is generally considered safe in non-allergic adults when taken in small doses. Use cautiously with G6PD deficiency or gallbladder disease. Menthol, which makes up part of peppermint oil, is generally considered safe in non-allergic adults. However, doses of menthol greater than 1 gram per kilogram of body weight may be deadly in humans. Avoid if pregnant or breastfeeding.
Probiotics: Probiotics are beneficial bacteria that are sometimes called friendly germs. They help maintain a healthy intestine and help the body digest foods. They also help keep harmful bacteria and yeasts in the gut under control. Most probiotics come from food sources, especially cultured milk products. Although probiotics have been suggested as a possible treatment for hives, there is currently insufficient scientific evidence on its safety and efficacy for this use.
Probiotics are generally considered safe and well tolerated. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.

Prevention

If possible, patients who are allergic to sunlight should minimize or avoid exposure to the sun. Patients should wear hats with brims, sunglasses, and protective clothing when outside to minimize exposure. An umbrella or parasol may also be beneficial in sensitive patients.
Allergic patients who cannot avoid exposure should apply sunblock to the skin whenever they are outside. This is because ultraviolet rays are able to penetrate clothing. Patients should choose a sunblock with a sun protection factor (SPF) of 15 or higher. The sunblock should offer protection against both ultraviolet A (UVA) and ultraviolet B (UVB) rays. Also, patients should look for products that are "PABA-free." PABA is a chemical that is found in many sunblocks, and it is know to cause irritation in sensitive patients.
Allergic patients should also use sunblock that is formulated especially for the lips. Patients should choose lip sunblock with an SPF of 20 or more.
Patients should not use tanning beds because they may trigger an allergic reaction.
Antihistamines like diphenhydramine (Bendaryl?) have been used to help prevent or reduce allergic reactions to sunlight.

Types of sun allergies

Actinic prurigo (hereditary PMLE): Actinic prurigo (hereditary PMLE) is an inherited sun allergy. This means the condition is passed down from parents to their children. Hereditary PMLE primarily occurs in patients of Native American ancestry. Symptoms of hereditary PMLE are generally the same as polymorphous light eruption (PMLE), but they are usually more severe. Also, symptoms usually begin during childhood or early adolescence.
Photoallergic eruption: Photoallergic eruption occurs when the sunlight interacts with a chemical that has been applied to the skin. For instance, this can occur with sunscreen, perfumes, cosmetics, or antibiotic ointments that have been applied to the skin. Photoallergic eruption can also occur if a chemical in a medication interacts with sunlight. Common prescription medications that lead to photoallergic eruptions include antibiotics (especially tetracyclines and sulfonamides), diuretics that are used to treat high blood pressure and heart failure, phenothiazines that are used to treat psychiatric illness, and certain oral contraceptives (birth control pills). Some herbs and supplements, including St. John's wort, may cause photoallergic eruption. Other potential causes may include nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Motrin? or Advil?) and naproxen (Aleve?).
Polymorphous light eruption (PMLE): Polymorphous light eruption (PMLE) is an allergic skin rash that develops after minimal exposure to sunlight. This condition primarily affects females between the ages of 20 and 40. For unknown reasons, men rarely develop this condition. PMLE typically affects individuals during the spring and summer months. Towards the end of the summer, after the individual has been exposed to sunlight multiple times, symptoms generally become less severe. However, next spring, allergic symptoms usually return with the original intensity.
Solar urticaria (hives): Patients with solar urticaria develop hives after sun exposure. Hives are red, raised itchy welts (wheals) of varying sizes on the surface of the skin.

Sun strength

Sunlight is made up of ultraviolet A (UVA) and ultraviolet B (UVB) rays. Individuals may be allergic to one type of ultraviolet ray or both.
The intensity of the sun's UV rays varies, depending on the time of day. The sun's rays are the strongest from 10:00 a.m. until 2:00 p.m.
In general, the ultraviolet rays of the sun are strongest during the warmest months of the year. Also, regions of the world that are closer to the equator receive the strongest sunlight. Altitude also influences a patient's susceptibility to sunlight. The higher the altitude, the thinner the air. For instance, UV exposure is stronger at the top of mountains than in the valleys.
Also, certain surfaces reflect more of the sun's rays than others. The ability of these surfaces to reflect light influences an individual's reaction to sun exposure. For instance, most natural surfaces, such as soil, grass, and water, reflect less than 10% of ultraviolet light, according to the World Health Organization (WHO). In contrast, sand reflects 10-25% and fresh snow reflects almost 80%. Therefore, sensitive patients who are exposed to sunlight in these conditions (e.g. at the beach or ski mountain) have the greatest risk of developing an allergic reaction.
The longer patients are exposed to the sun, the more UV rays they receive and the more intense the allergic reaction.