Urtica dioica

Nettle/Drug Interactions:

  • 5-Alpha reductase inhibitors5-Alpha reductase inhibitors: 30% methanol extract of Urtica dioica roots (10:1) markedly reduced activity of 5-alpha reductase in rats (59).
  • AbortifacientsAbortifacients: In animal research, nettle caused uterine contractions (1).
  • Alpha-1 adrenergic blockersAlpha-1 adrenergic blockers: Prazosin, doxazosin and terazosin have been associated with a "first-dose" effect. Marked hypotension, especially postural hypotension, and syncope with sudden loss of consciousness can occur with the first few doses. An aqueous extract of aerial parts of the nettle plant administered to male rats demonstrated an acute hypotensive action (3). Coadministration of nettle and an alpha-1 blocker may have an additive hypotensive effect. Alpha-1 adrenergic blockers are also used in the treatment of benign prostate hyperplasia. Coadministration of alpha-1 blockers and nettle may result in additive effects on a hypotensive crisis (36; 18; 19; 20; 22; 24; 25; 37; 38; 28; 29; 30).
  • AnalgesicsAnalgesics: Stinging nettle demonstrated an analgesic effect and reduction of disability after one week of daily treatment; however, the mechanism is unclear (33).
  • AntiarthriticsAntiarthritics: Nettle is widely used as a folk remedy to treat arthritic and rheumatic conditions. Preclinical evidence and in vitro and in vivo effects suggests that certain constituents in the nettle plant have anti-inflammatory and/or immunomodulatory activity (13). A nonrandomized trial evaluating stinging nettle cream reported reduction in WOMAC scores (42). A combination trial evaluating Phytalgic (fish oil, vitamin E, and Urtica dioica) reported a decrease in NSAID and analgesic use and improvement in osteoarthritis symptoms (60). Christensen et al. commented on this trial and reported that the results from this trial are promising (61).
  • AntibioticsAntibiotics: An oral combination product containing Urtica dioica improved the efficacy of prulifloxacin in chronic bacterial prostatitis in humans (62).
  • AnticoagulantsAnticoagulants: Nettle root contains a coumarin constituent (34; 6; 8). Therefore, administration of nettle root may potentiate the effects of anticoagulants. Nettle leaves contain vitamin K (8). High doses may alter response to warfarin.
  • AntidiabeticsAntidiabetics: Oral ingestion of nettle resulted in aggravation of the diabetic condition in streptozotocin diabetic mice (45). An aqueous extract of nettle leaves administered to healthy rabbits with temporarily induced hyperglycemia caused a slight increase in glycemia (statistical significance was lacking) (44). In contrast, a 78 year-old diabetic man reported hypoglycemia after ingesting an herbal remedy for benign prostatic hyperplasia (BPH); however, details are lacking regarding the contents of the remedy (56).
  • AntifungalsAntifungals: Isolated lectins from nettle root extracts had fungistatic effects in vitro (63; 2).
  • Antigout agentsAntigout agents: According to secondary sources, nettle may interact with agents used for gout.
  • AntihistaminesAntihistamines: According to secondary sources, nettle may interact with antihistamines. Histamine has been found in the stinging hairs of stinging nettle. Taskila et al. found that in stinging nettle-induced urticaria, there was a weak release of histamine (64). Tingling, itching, burning, pain, numbness, blistering, and rash have been reported in human research (39; 40; 8; 33; 41; 42; 43). Two patients taking a freeze-dried preparation of Urtica dioica for the treatment of allergic rhinitis in a randomized controlled trial withdrew due to an intensification of allergy symptoms (31). A case of generalized urticaria in a 17 day-old neonate from topical application of nettle to the mother's nipple has been reported (48). The neonate was reportedly rushed to the emergency room.
  • AntihypertensivesAntihypertensives: An aqueous extract of aerial parts of the nettle plant administered to male rats demonstrated an acute hypotensive action (3).
  • Anti-inflammatoriesAnti-inflammatories: In humans, stewed nettle leaves plus diclofenac 50mg were as effective in the treatment of acute arthritis as diclofenac 200mg (32). According to human research, a hydroalcoholic extract of stinging nettle was found to lower levels of interleukin-6 and high-sensitivity C-reactive protein (hs-CRP), but it lacked significant effects on TNF-alpha (46)
  • AntineoplasticsAntineoplastics: In preliminary research, it was suggested that compounds from stinging nettle may induce differentiation (6).
  • AntiretroviralsAntiretrovirals: The (N-acetylglucosamine)n-specific lectin from Urtica dioica (UDA) demonstrated in vitro inhibitory activity against HIV-1-, HIV-2-, CMV-, RSV- and influenza A virus-induced cytopathicity (5; 6). The relevance of these in vitro findings remains unclear. Urtica dioica agglutinin (UDA) inhibited the entry of HIV into its target cells through the mechanism of gp120 glycan binding in vitro (35).
  • Dermatologic agentsDermatologic agents: Tingling, itching, burning, pain, numbness, blistering, and rash have been reported in human research (39; 40; 8; 33; 41; 42; 43).
  • Disulfiram (Antabuse?)Disulfiram (Antabuse?): Stinging nettle extracts often contain an alcohol content of up to 45% (46; 47).
  • DiureticsDiuretics: An aqueous extract of aerial parts of nettle administered to male rats demonstrated diuretic and natriuretic effects (3).
  • FinasterideFinasteride: Finasteride, a 5-alpha reductase inhibitor, is used in the treatment of benign prostatic hyperplasia. Coadministration of finasteride and nettle may have additive effects as both inhibit the enzyme (36; 18; 19; 20; 22; 24; 25; 37; 38; 28; 29; 30).
  • Gastrointestinal agentsGastrointestinal agents: Gastric discomfort, diarrhea, constipation, and hyperperistalsis have been reported in human research (23; 31; 36; 29).
  • Genitourinary tract agentsGenitourinary tract agents: In animal research, nettle caused uterine contractions (1). In a randomized controlled trial, patients taking Bazoton ? uno for benign prostatic syndrome experienced urinary tract infections, urinary obstruction, and hematuria (58). However, the authors reported that these events also occurred in the placebo group. According to in vitro research, nettle root seems to have antiprostatic effects due to sex hormone-binding globulin (SHBG), aromatase, epidermal growth factor, and prostate steroid membrane receptors, and lack significant effects from 5-alpha reductase and androgen receptors (63). In human research, Bazoton? Liqidum reduced residual and prostatic volume, and increased maximal urinary flow and micturition volume (21). Human research also demonstrated a decrease in prostate size with 120mg of root extract of Urtica dioica (52).
  • Hematological agentsHematological agents: Nettle root contains a coumarin constituent (34; 6; 8). Therefore, administration of nettle root may potentiate the effects of anticoagulants. Nettle leaves contain vitamin K (8). High doses may alter response to warfarin. In a chronic toxicity study in which nettle infusion was administered to Wistar rats via an intragastric probe, nasal, oral, and orbital bleeding was observed (34); upon autopsy, pulmonary edema and blood at the intestinal lumen were found. Coagulation time was delayed for seven days in the rats and was also determined to be the cause of death. According to a cross-sectional analysis, women taking traditional Chinese medicine herbs, such as nettle, had 21% higher serum lead levels than nonusers (54).
  • Metronidazole (Flagyl?)Metronidazole (Flagyl?): A disulfiram reaction may occur when metronidazole and alcohol are used concomitantly. Stinging nettle extracts often contain an alcohol content of up to 45% (46; 47).
  • Neurologic agentsNeurologic agents: Intermittent headache and fatigue were reported in one patient in an equivalence trial of 134 patients when two capsules of Prostatonin Pharmaton? were administered daily for eight weeks (23).
  • OxytocicsOxytocics: In animal research, nettle caused uterine contractions (1).
  • Renal agentsRenal agents: An aqueous extract of aerial parts of nettle administered to male rats demonstrated diuretic and natriuretic effects, suggesting an action on renal function (3).
  • Respiratory agentsRespiratory agents: Two patients taking freeze-dried Urtica dioica withdrew from a trial due to intensification of their allergic rhinitis symptoms (31).
  • SedativesSedatives: According to secondary sources, nettle may interact with sedatives.
  • VasodilatorsVasodilators: According to secondary sources, nettle may interact with vasodilators.

    • Nettle/Herb/Supplement Interactions:

  • 5-Alpha reductase inhibitors5-Alpha reductase inhibitors: 30% methanol extract of Urtica dioica roots (10:1) markedly reduced activity of 5-alpha reductase in rats (59).
  • AbortifacientsAbortifacients: In animal research, nettle caused uterine contractions (1).
  • Alpha-1 adrenergic blockersAlpha-1 adrenergic blockers: Prazosin, doxazosin, and terazosin have been associated with a "first-dose" effect. Marked hypotension, especially postural hypotension, and syncope with sudden loss of consciousness can occur with the first few doses. An aqueous extract of aerial parts of the nettle plant administered to male rats demonstrated an acute hypotensive action (3). Coadministration of nettle and an alpha-1 blocker may have an additive hypotensive effect. Alpha-1 adrenergic blockers are also used in the treatment of benign prostate hyperplasia. Coadministration of alpha-1 blockers and nettle may result in additive effects of hypotensive crisis (36; 18; 19; 20; 22; 24; 25; 37; 38; 28; 29; 30)
  • AnalgesicsAnalgesics: Stinging nettle demonstrated an analgesic effect and reduction of disability after one week of daily treatment; however, the mechanism is unclear (33).
  • AntiarthriticsAntiarthritics: Nettle is widely used as a folk remedy to treat arthritic and rheumatic conditions. Preclinical evidence and in vitro and in vivo effects suggests that certain constituents in the nettle plant have anti-inflammatory and/or immunomodulatory activity (13). A nonrandomized trial evaluating stinging nettle cream produced a reduction in WOMAC scores (42). A combination trial evaluating Phytalgic (fish oil, vitamin E, and Urtica dioica) produced a decrease in NSAID and analgesic use and improvement in osteoarthritis (OA) symptoms (60). Christensen et al. commented on this trial and reported that the results from this trial are promising (61).
  • AntibacterialsAntibacterials: An oral combination product containing Urtica dioica improved the efficacy of prulifloxacin in chronic bacterial prostatitis (62).
  • AnticoagulantsAnticoagulants: Nettle root contains a coumarin constituent (34; 6; 8). Therefore, administration of nettle root may potentiate the effects of anticoagulants. Nettle leaves contain vitamin K (8). High doses may alter response to warfarin.
  • AntifungalsAntifungals: Isolated lectins from nettle root extracts had fungistatic effects in vitro (63; 2).
  • Antigout agentsAntigout agents: According to secondary sources, nettle may interact with agents used for gout.
  • AntihistaminesAntihistamines: According to secondary sources, nettle may interact with antihistamines. Histamine has been found in the stinging hairs of stinging nettle. Taskila et al. found that in stinging nettle-induced urticaria, there was a weak release of histamine (64). Tingling, itching, burning, pain, numbness, blistering, and rash have been reported in human research (39; 40; 8; 33; 41; 42; 43). Two patients taking a freeze-dried preparation of Urtica dioica for the treatment of allergic rhinitis in a randomized controlled trial withdrew due to an intensification of allergy symptoms (31). A case of generalized urticaria in a 17 day-old neonate from topical application of nettle to the mother's nipple has been reported (48). The neonate was reportedly rushed to the emergency room.
  • Anti-inflammatoriesAnti-inflammatories: In humans, stewed nettle leaves plus diclofenac 50mg were as effective in the treatment of acute arthritis as diclofenac 200mg (32). According to human research, a hydroalcoholic extract of stinging nettle was found to lower levels of interleukin-6 and high-sensitivity C-reactive protein (hs-CRP), but it lacked significant effects on TNF-alpha (46)
  • AntineoplasticsAntineoplastics: In preliminary research, it was suggested that compounds from stinging nettle may induce differentiation (6).
  • AntioxidantsAntioxidants: Hydroalcoholic extracts of stinging nettle demonstrated effects on oxidative stress by increasing superoxidant dismutase and decreasing total antioxidant capacity, but they lacked significant effects on glutathione peroxides and malondialdehyde (4).
  • AntiretroviralsAntiretrovirals: The (N-acetylglucosamine)n-specific lectin from Urtica dioica (UDA) demonstrated in vitro inhibitory activity against HIV-1-, HIV-2-, CMV-, RSV- and influenza A virus-induced cytopathicity (5; 6). The relevance of these in vitro findings remains unclear. Urtica dioica agglutinin (UDA) inhibited the entry of HIV into its target cells through the mechanism of gp120 glycan binding in vitro (35).
  • Dermatologic agentsDermatologic agents: Tingling, itching, burning, pain, numbness, blistering, and rash have been reported in human research (39; 40; 8; 33; 41; 42; 43).
  • DiureticsDiuretics: An aqueous extract of aerial parts of nettle administered to male rats demonstrated diuretic and natriuretic effects (3).
  • Dong quaiDong quai: Both nettle and dong quai contain natural coumarin derivatives (6; 8). Combined use may increase risk of bleeding.
  • Fish oilFish oil: An oral combination product containing fish oil, vitamin E, and Urtica dioica produced additive effects in the treatment of knee and hip osteoarthritis in humans (60).
  • Gastrointestinal agentsGastrointestinal agents: Gastric discomfort, diarrhea, constipation, and hyperperistalsis have been reported in human research (23; 31; 36; 29).
  • Genitourinary tract agentsGenitourinary tract agents: In animal research, nettle caused uterine contractions (1). In a randomized controlled trial, patients taking Bazoton ? uno for benign prostatic syndrome experienced urinary tract infections, urinary obstruction, and hematuria (58). However, the authors reported that these events also occurred in the placebo group. According to in vitro research, nettle root seems to have antiprostatic effects due to sex hormone-binding globulin (SHBG), aromatase, epidermal growth factor, and prostate steroid membrane receptors, and lack significant effects from 5-alpha reductase and androgen receptors (63). In human research, Bazoton? Liqidum reduced residual and prostatic volume, and increased maximal urinary flow and micturition volume (21). Human research also demonstrated a decrease in prostate size with 120mg of root extract of Urtica dioica (52).
  • HematologicsHematologics: Nettle root contains a coumarin constituent (34; 6; 8). Therefore, administration of nettle root may potentiate the effects of anticoagulants. Nettle leaves contain vitamin K (8). High doses may alter response to warfarin. In a chronic toxicity study in which nettle infusion was administered to Wistar rats via an intragastric probe, nasal, oral, and orbital bleeding was observed (34); upon autopsy, pulmonary edema and blood at the intestinal lumen were found. Coagulation time was delayed for seven days in the rats and was also determined to be the cause of death. According to a cross-sectional analysis, women taking traditional Chinese medicine herbs, such as nettle, had 21% higher serum lead levels than nonusers (54).
  • Horse chestnutHorse chestnut: Horse chestnut has exhibited additive antithrombotic activity with warfarin. Nettle contains a coumarin derivative (6; 8). Combined use may increase the risk of bleeding.
  • Hypoglycemics/hyperglycemicsHypoglycemics/hyperglycemics: Oral ingestion of nettle resulted in aggravation of the diabetic condition in streptozotocin diabetic mice (45). An aqueous extract of nettle leaves administered to healthy rabbits with temporarily induced hyperglycemia caused a slight increase in glycemia (statistical significance was lacking) (44). In contrast, a 78 year-old diabetic man reported hypoglycemia after ingesting an herbal remedy for BPH; however, details are lacking regarding the contents of the remedy (56).
  • Hypotensives/hypertensivesHypotensives/hypertensives: An aqueous extract of aerial parts of the nettle plant administered to male rats demonstrated an acute hypotensive action (3).
  • KavaKava: Kava has exhibited additive antithrombotic activity with warfarin. Nettle contains a coumarin derivative (6; 8). Combined use may increase risk of bleeding.
  • Neurologic agentsNeurologic agents: Intermittent headache and fatigue were reported in one patient in an equivalence trial of 134 patients when two capsules of Prostatonin Pharmaton? were administered daily for eight weeks (23).
  • NiacinNiacin: Niacin has been associated with small but significant increase in prothrombin time (mean increase: 4%), according to secondary sources.
  • OxytocicsOxytocics: In animal research, nettle caused uterine contractions (1).
  • PygeumPygeum: Pygeum is used to treat benign prostatic hyperplasia (65; 23).
  • Renal agentsRenal agents: An aqueous extract of aerial parts of nettle administered to male rats demonstrated diuretic and natriuretic effects, suggesting an action on renal function (3).
  • Respiratory agentsRespiratory agents: Two patients taking freeze-dried Urtica dioica withdrew from a trial due to intensification of their allergic rhinitis symptoms (31).
  • Saw palmettoSaw palmetto: Saw palmetto is used to treat benign prostatic hyperplasia (65; 26; 27).
  • SedativesSedatives: According to secondary sources, nettle may interact with sedatives.
  • Soy isoflavonesSoy isoflavones: Soy isoflavones appear to inhibit type II 5-alpha reductase, according to secondary sources.
  • VasodilatorsVasodilators: According to secondary sources, nettle may interact with vasodilators.
  • Vitamin EVitamin E: An oral combination product containing fish oil, vitamin E, and Urtica dioica produced additive effects in treatment of knee and hip osteoarthritis in humans (60).

    • Nettle/Food Interactions:

  • Insufficient available evidence.

    • Nettle/Lab Interactions:

  • Blood pressureBlood pressure: An aqueous extract of aerial parts of the nettle plant administered to male rats demonstrated an acute hypotensive action (3).
  • GlucoseGlucose: Oral ingestion of nettle resulted in aggravation of the diabetic condition in streptozotocin diabetic mice (45). An aqueous extract of nettle leaves administered to healthy rabbits with temporarily induced hyperglycemia caused a slight increase in glycemia (statistical significance was lacking) (44). In contrast, a 78 year-old diabetic man reported hypoglycemia after ingesting an herbal remedy for BPH; however, details are lacking regarding the contents of the remedy (56).
  • Inflammatory markersInflammatory markers: According to human research, a hydroalcoholic extract of stinging nettle was found to lower levels of interleukin-6 and high-sensitivity C-reactive protein (hs-CRP), but it lacked significant effects on TNF-alpha (46).
  • Prothrombin time/INR (international normalized ratio)Prothrombin time/INR (international normalized ratio): Nettle root contains a coumarin constituent (34; 6; 8). Therefore, administration of nettle root may potentiate the effects of anticoagulants. Nettle leaves contain vitamin K (8). High doses may alter the response to warfarin.
  • Serum lead levelsSerum lead levels: According to a cross-sectional analysis, women taking traditional Chinese medicine herbs, such as nettle, had 21% higher serum lead levels than nonusers (54).
  • SodiumSodium: An aqueous extract of aerial parts of nettle administered to male rats demonstrated diuretic and natriuretic effects, suggesting an action on renal function (3).