Arnica

Arnica/Drug Interactions:

  • AbortifacientsAbortifacients: Internal use of arnica is contraindicated in pregnancy due to potential for uterine stimulation (from animal and in vitro data) and toxicity (10).
  • AnalgesicsAnalgesics: Based on a randomized clinical trial, homeopathic arnica 30C may reduce subjective pain scores in tonsillectomy patients and in individuals undergoing lumbago treatment (43; 25). In a systematic review, the authors concluded that arnica may have a beneficial effect on pain and bruising when used in combination with dermatologic surgery, but lacked effect when used after carpal tunnel surgery (32). In a clinical trial, short-term use of arnica gel was as effective for treatment of hand osteoarthritis pain as ibuprofen gel (56). In a clinical trial, topical arnica decreased pain, stiffness, and restriction-of-function in individuals with knee osteoarthritis (26).
  • AnestheticsAnesthetics: According to one survey of 601 children presenting for day surgery, the use of herbal products may have serious interactions with anesthetic drugs. Arnica was one of the most common herbals used by children, and this may have implications for the perioperative management of children presenting for surgery (14).
  • Antiarrhythmic agentsAntiarrhythmic agents: According to a safety report and a clinical trial, ingestion of arnica extracts has been reported to cause accelerated heartbeat (10; 11).
  • Anticoagulants and antiplateletsAnticoagulants and antiplatelets: Arnica montana has been shown to increase bleeding time by inhibition of platelet aggregation in vitro (7), although no change in bleeding time was observed in a clinical trial using a homeopathic dose of arnica (64). Extensive intra-operative bleeding was reported in an individual supplementing arnica one day prior to the operation (8). In a clinical trial, two cases of bleeding during surgery were reported in the arnica group (9).
  • AntidepressantsAntidepressants: Homeopathic arnica (6C) has been reported to cause depressed feelings, specifically a feeling of unhappiness (13).
  • AntihypertensivesAntihypertensives: Based on anecdote, arnica may reduce the effectiveness of antihypertensives. Arnica was listed in a review of herbal products that may cause hypertension (12).
  • Anti-inflammatory agentsAnti-inflammatory agents: Based on a randomized controlled trial, arnica may reduce edema during the early postoperative period (31). In a clinical trial, topical arnica decreased pain, stiffness, and restriction-of-function in individuals with knee osteoarthritis (26). In a clinical trial, short-term use of arnica gel was as effective for treatment of hand osteoarthritis pain as ibuprofen gel (56).
  • AntilipemicsAntilipemics: Based on animal evidence, sesquiterpene lactones may block lipogenesis, resulting in lowering of serum lipids (65).
  • AntineoplasticsAntineoplastics: The effects of sesquiterpene lactones as dual cancer therapy and inhibition of leukaemia cell growth were reviewed (66).
  • CNS stimuantsCNS stimuants: Homeopathic arnica has been reported to cause drowsiness (at 6C dose) (13).
  • CorticosteroidsCorticosteroids: Based on a randomized controlled trial, arnica may reduce edema during the early postoperative period (31).
  • Dermatologic agentsDermatologic agents: Allergic hypersensitivity reactions have been commonly reported in case reports. Reactions including Sweet's syndrome, erythematous papules, facial eczema, and oral mucosal lesions have been noted in case reports (15; 16; 17; 18; 19; 20; 21).
  • Gastrointestinal agentsGastrointestinal agents: Ingestion of A. montana-containing extracts has induced severe gastroenteritis, including gastrointestinal problems due to mucosal irritation nervousness, nausea, and vomiting (10).
  • Hydroxyethyl salicylateHydroxyethyl salicylate: Based on a study of healthy humans, topical arnica may increase hydroxyethyl salicylate's analgesic effect (67).
  • Neurologic agentsNeurologic agents: Homeopathic arnica has been reported to cause headache (at 30C dose) and drowsiness (at 6C dose) (13). Topical application of arnica gel resulted in reports of vertigo in a clinical trial (56).

    • Arnica/Herb/Supplement Interactions:

  • AbortifacientsAbortifacients: Internal use of arnica is contraindicated in pregnancy due to potential for uterine stimulation (from animal and in vitro data) and toxicity (10).
  • AnalgesicsAnalgesics: Based on a randomized clinical trial, homeopathic arnica 30C may reduce subjective pain scores in tonsillectomy patients and in individuals undergoing lumbago treatment (43; 25). In a systematic review, the authors concluded that arnica may have a beneficial effect on pain and bruising when used in combination with dermatologic surgery, but lacked effect when used after carpal tunnel surgery (32). In a clinical trial, short-term use of arnica gel was as effective for treatment of hand osteoarthritis pain as ibuprofen gel (56). In a clinical trial, topical arnica decreased pain, stiffness, and restriction-of-function in individuals with knee osteoarthritis (26).
  • AnestheticsAnesthetics: According to one survey of 601 children presenting for day surgery, the use of herbal products may have serious interactions with anesthetic drugs. Arnica was one of the most common herbals used by children, and this may have implications for the perioperative management of children presenting for surgery (14).
  • Antiarrhythmic herbs and supplementsAntiarrhythmic herbs and supplements: According to a safety report and a clinical trial, ingestion of arnica extracts has been reported to cause accelerated heartbeat (10; 11).
  • Anticoagulants and antiplateletsAnticoagulants and antiplatelets: Arnica may enhance bleeding if taken with other anticoagulants, due to arnica's theoretical inhibition of platelet activation. Arnica montana has been shown to increase bleeding time by inhibition of platelet aggregation in vitro (7), although no change in bleeding time was observed in a clinical trial using a homeopathic dose of arnica (64). Extensive intra-operative bleeding was reported in an individual supplementing arnica one day prior to the operation (8). In a clinical trial, two cases of bleeding during surgery were reported in the arnica group (9).
  • AntidepressantsAntidepressants: Homeopathic arnica (6C) has been reported to cause depressed feelings, specifically a feeling of unhappiness (13).
  • Anti-inflammatory herbsAnti-inflammatory herbs: Based on a randomized controlled trial, arnica may reduce edema during the early postoperative period (31). In a clinical trial, topical arnica decreased pain, stiffness, and restriction-of-function in individuals with knee osteoarthritis (26). In a clinical trial, short-term use of arnica gel was as effective for treatment of hand osteoarthritis pain as ibuprofen gel (56).
  • AntilipemicsAntilipemics: Sesquiterpene lactones block lipogenesis, resulting in lowering of serum lipids in mice (65).
  • Antineoplastic herbs and supplementsAntineoplastic herbs and supplements: The effects of sesquiterpene lactones as dual cancer therapy and inhibition of leukaemia cell growth were reviewed (66).
  • Bellis perennisBellis perennis: Arnica used in conjunction with B. perennis may reduce postpartum blood loss (68).
  • Dermatologic herbs and supplementsDermatologic herbs and supplements: Allergic hypersensitivity reactions have been commonly reported in case reports. Reactions including Sweet's syndrome, erythematous papules, facial eczema, and oral mucosal lesions have been noted in case reports (15; 16; 17; 18; 19; 20; 21).
  • Gastrointestinal herbs and supplementsGastrointestinal herbs and supplements: Ingestion of A. montana-containing extracts has induced severe gastroenteritis, including gastrointestinal problems due to mucosal irritation nervousness, nausea, and vomiting (10).
  • HypotensivesHypotensives: Based on anecdote, arnica may reduce the effectiveness of antihypertensives. Arnica was listed in a review of herbal products that may cause hypertension (12).
  • Neurologic agentsNeurologic agents: Homeopathic arnica has been reported to cause headache (at 30C dose) and drowsiness (at 6C dose) (13). Topical application of arnica gel resulted in reports of vertigo in a clinical trial (56).
  • Stimulant herbs and supplementsStimulant herbs and supplements: Homeopathic arnica has been reported to cause drowsiness (at 6C dose) (13).

    • Arnica/Food Interactions:

  • Insufficient available evidence.

    • Arnica/Lab Interactions:

  • Blood pressureBlood pressure: Based on anecdote, arnica may reduce the effectiveness of antihypertensives and alter blood pressure control. Arnica was listed in a review of herbal products that may cause hypertension (12).
  • Coagulation panelCoagulation panel: Arnica may increase coagulation time (7). Extensive intra-operative bleeding was reported in an individual supplementing arnica one day prior to the operation (8). In a clinical trial, two cases of bleeding during surgery were reported in the arnica group (9).
  • Lipid panelLipid panel: Theoretically, the sesquiterpene lactones in arnica may block lipogenesis, resulting in lowering of serum lipids (65).
  • Protein bindingProtein binding: Arnica may affect protein binding and therefore may alter the interpretation of in vitro and ex vivo assays (69).