List of herbs with known adverse effects

This is a partial list of herbs and herbal treatments with known or suspected adverse effects, either alone or in interaction with other herbs or drugs. Non-inclusion of an herb in this list does not imply that it is free of adverse effects. In general, the safety and effectiveness of alternative medicines have not been scientifically proven[1] and remain largely unknown.[2] Beyond adverse effects from the herb itself, "adulteration, inappropriate formulation, or lack of understanding of plant and drug interactions have led to adverse reactions that are sometimes life threatening or lethal."[3]

Most of the adverse effects stated in this list are associated with only a small percentage of cases; they should be understood as potential risks rather than as certainties.

Herbs, treatments, and constituents with known or suspected adverse effects

Name	Other common names	Scientific name	Adverse effects
Aconite	monkshood, wolfsbane, aconitum[4]	Aconitum spp.	Heart palpitations and arrhythmias, hypotension, nausea, vomiting, abdominal pain, respiratory system paralysis, death[4][5]
Aloe vera juice	medicinal aloe	Aloe vera	"abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents"[3]
Anthranoid laxatives			"abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents"[3]
Areca nut	betel nut	Areca catechu	"deterioration of psychosis in patients with preexisting psychiatric disorders";[5] known carcinogen contributing to cancer of the mouth, pharynx, esophagus and stomach when chewed.[6]
Aristolochic acid (contained in herbs in the genus Aristolochia e.g. Aristolochia serpentaria (Virginia snakeroot), Aristolochia reticulata (Texas snakeroot) and in Chinese herbs such as Aristolochia fangchi and Aristolochia_manshuriensis[7] (banned in China and withdrawn from Chinese Pharmacopoea 2005; Stephania tetrandra and Magnolia officinalis do not contain aristolochic acid).			Kidney toxicity[5] associated with kidney failure; associated with development of cancer, particularly of the urinary tract, known carcinogen[8][9]
Atractylate		Atractylis gummifera	Liver damage,[3] nausea, vomiting, epigastric and abdominal pain, diarrhoea, anxiety, headache and convulsions, often followed by coma[10]
Ayurvedic Herbo-mineral (Rasashastra) Medicines			Heavy metal contamination[11]
Bitter orange			'Fainting, arrhythmia, heart attack, stroke, death'[4]
Broom	broom flower, dyer's broom, dyer's greenwood, dyer's weed, dyer's whin, furze, green broom, greenweed, wood waxen[12]	Genista tinctoria[12]	Uterotonic properties,[5] nausea vomiting, and diarrhea,[12] contraindicated for pregnancy and breast feeding[12]
Buckthorn bark and berry	alder buckthorn	Rhamnus frangula	"abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents"[3]
Cascara Sagrada bark	bearberry	Rhamnus purshiana	"abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents"[3]
Chaparral	creosote bush, gobernadora, larreastat[4]	Larrea tridentata, Larrea divaricata[4]	Liver damage,[3][4][5] kidney problems,[4] Hypotension in cancer patients[3]
Chinese herbal mixtures			Heavy metal poisoning[5]
Coltsfoot	coughwort, farfarae folium leaf, foalswort[4]	Tussilago farfara	Liver damage, cancer[4]
Comfrey	comphrey, blackwort, common comfrey, slippery root[4]	Symphytum officinale	Liver damage,[4][5] cancer[4]
Country mallow	heartleaf, silky white mallow	Sida cordifolia	"Heart attack, heart arrhythmia, stroke, death"[4]
Dan Shen	red sage, Chinese sage, tan shen	Salvia miltiorrhiza	Potentiates warfarin activity, leading to excessive anticoagulation and bleeding[3][13]
Dong quai	female ginseng	Angelica sinensis	May induce uterine contractions; contraindicated when pregnant or nursing[14]
European Mistletoe	common mistletoe	Viscum album	Toxic to cardio and central nervous systems, gastrointestinal bleeding[3]
Ephedra	ma huang	Ephedra sinica	Agitation and palpitations,[3] "hypertension, irregular heart rate, insomnia, nervousness, tremors and seizures, paranoid psychoses, heart attacks, strokes, and death",[1][15] kidney stones[15]
Flavonoids (contained in many medicinal plants)[5]	Vitamin P, citrin	Flavonoids, bioflavonoids	Hemolytic anemia, kidney damage[5]
Germander		Teucrium	Liver damage[3][5]
Ginger		Zingiber officinale	May increase the risk of bleeding[16]
Ginkgo	gingko	Ginkgo biloba	Bleeding[15][16]
American Ginseng	American Ginseng, Canadian Ginseng, Ginseng, Ginseng Root, North American Ginseng, Occidental Ginseng, Ontario Ginseng, Panax quinquefolium, Panax quinquefolius, Red Berry, Ren Shen, Sang, Shang, Shi Yang Seng, Wisconsin Ginseng[17]	Panax quinquefolius	"Hypertensive and chronotropic activities, may increase digoxin levels",[3] diarrhea, itching, insomnia, headaches, nervousness, rapid heartbeat, hypertension or hypotension, breast tenderness, vaginal bleeding. Very rarely Stevens–Johnson syndrome, liver damage, severe allergy has been reported[17] May lower blood sugar excessively in combination with diabetes medication.[17] Contains a chemical linked to possible birth defects.[17] May worsen hormone sensitive conditions such as breast cancer, uterine cancer, ovarian cancer, endometriosis, and uterine fibroids.[17] Insomnia.[17]
Goldenseal	orangeroot, yellow puccoon	Hydrastis canadensis	Uterotonic[3]
Greater celandine	celandine	Chelidonium majus	Liver damage[4]
Guarana		Paullinia cupana	Agitation and insomnia[3]
Guar gum	guaran		Obstruction of gastrointestinal tract[5]
Gugulipid	guggal, guggul, Mukul myrrh tree	Commiphora mukul	"Headache, nausea, hiccups, diminished efficacy of other cardiovascular drugs including diltiazem and propranolol"[3]
Hawthorn	common hawthorn, may, mayblossom, maythorn, quickthorn, whitethorn, motherdie, haw	Crataegus monogyna	"Potentiates digitalis activity, increases coronary dilation effects of theophylline, caffeine, papaverine, sodium nitrate, adenosine and epinephrine, increase barbiturate-induced sleeping times"[3]
Horse chestnut	conker tree, conker	Aesculus hippocastanum	Liver toxicity, allergic reaction, anaphylaxis[3]
Kava	awa, kava-kava[4]	Piper methysticum	Potentates CNS sedatives,[3] chronic use might cause a reversible dry skin condition.[18]
Khat	qat	Catha edulis	Chronic liver dysfunction[3][19]
Kratom		Mitragyna speciosa	Hepatotoxicity[20][19]
Liquorice root		Glycyrrhiza glabra	Hypokalemia, hypertension, arrhythmias, edema[5]
Lobelia	asthma weed, pukeweed, vomit wort	Lobelia inflata	Toxicity, rapid heartbeat, hypotension, coma, death[4]
Milk thistle	Marian thistle	Silybum marianum	Mild laxative, allergy[5]
Pennyroyal		Mentha pulegium	Liver damage[3][5]
Peony	Bai Shao, Chi Shao, Chinese peony, common peony, coral peony, Cortex Moutan, European peony, Jiu Chao Bai Shao, Moutan, Mu Dan PI, peony flower, peony root, piney, radix peony, red peony, Shakuyaku, Shao Yao, tree peony, Ud Saleeb, Udsalam, Udsalap, White Peony[21]	Radix Paeoniae, Radix Paeoniae Alba, Radix Paeoniae Rubra, Paeonia, Paeonia alba, Paeonia lactiflora, Paeonia mascula; Paeonia obovata; Paeonia officinalis; Paeonia suffruticosa, Paeonia veitchii, Paeoniae Flos, Paeoniae Radix[21]	May slow clotting; contraindicated for people with bleeding disorders and before and after surgery. May induce uterine contractions; contraindicated when pregnant or nursing.[21]
Pyrrolizidine alkaloids (contained in comfrey, borage, senecio, coltsfoot, and others)			Liver damage[5]
Reserpine		Rauvolfia serpentina	"Sedation, inability to complete tasks, mental depression, nasal congestion, increased gastric secretion and mild diarrhea"[3]
Safrole		Sassafras albidum	Liver damage[3]
Saw palmetto		Serenoa repens	"rare and mild gastrointestinal upset, headaches, diarrhea, gynecomastia, paroxysmal atrial fibrillation, ventricular rupture and death in one patient"[3]
Senna	Egyptian senna	Senna alexandrina (Cassia senna)	"abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents",[3] liver damage[3]
St John's wort	Tipton's weed, Klamath weed	Hypericum perforatum	Photosensitization,[3][15] GI disturbances, "allergic reactions, fatigue, dizziness, confusion, dry mouth"[15]
Valerian	garden valerian, garden heliotrope, all-heal	Valeriana officinalis	"drowsiness, GI upset, headache, palpitations, insomnia",[3] oversedation, overstimulation[16]
Vasambu	sweet flag	Acorus calamus	Vomiting and nausea[22]
Yohimbe	yohimbine	Pausinystalia johimbe	rapid heart rate, hypertension, hypotension, heart problems, death[4]

Herbs with adverse drug interactions

Name	Other common names	Scientific name	Drug	Adverse effects
Cinchona bark		Cinchona pubescens	Warfarin	Possibly additive[3]
Chamomile			Blood thinners[23]
Devil's Claw	grapple plant, wood spider	Harpagophytum	Warfarin	Additive effects[3]
Ephedra		Ephedra	Caffeine, decongestants, stimulants[15]
Feverfew	featherfew	Tanacetum parthenium	Aspirin	Additive effects[3]
Garlic		Allium sativum	Warfarin	Additive effects[3]
Ginger		Zingiber officinale	Warfarin	Additive effect, causes iris bleeding[3]
Ginkgo	gingko	Ginkgo biloba	Aspirin, warfarin, ticlopidine, clopidogrel, dipyridamole, garlic, vitamin E[15]	With aspirin - retards aspirin absorption[3]
Ginseng		Panax ginseng	Warfarin[15]
Papaya extract		Carica papaya	Warfarin	Damage to GI tract mucous membranes, Possibly additive, purpura[3]
Kava	kava-kava	Piper methysticum	Sedatives, sleeping pills, antipsychotics, alcohol[15]
Milkvetch		Astragalus	Astragalus may interact with medications that suppress the immune system, such as cyclophosphamide.[24]	It may also affect blood sugar levels and blood pressure.
Pineapple enzyme		Ananas comosus	Bromelain	"Diarrhea, increased tendency for bleeding if used simultaneously with anticoagulants and inhibitors of thrombocytic aggregation due to modulation of the arachidonate cascade"[3]
Psyllium seed		Plantago spp	Coumarin derivates	Retards absorption of drug[3]
St John's wort	Tipton's weed, Klamath weed	Hypericum perforatum	Antidepressants,[15][16] warfarin, protease inhibitors for HIV, birth control, some asthma drugs, and many other medications[16]

Herbal plants associated with allergic reactions

• Angelica[5]
• Aniseed[5]
• Apricot[5]
• Arnica[5]
• Artichoke[5]
• Asafoetida[5]
• Boneset[5]
• Cassia[5]
• Celery[5]
• Cinnamon[5][25]
• Cowslip[5]
• Dandelion[5]
• Elecampane[5]
• Euphorbia[5]
• Feverfew[5]
• Filipendula[5]
• Fucus[5]
• Gravel root[5]
• Guaiacum[5]
• Holy Thistle[5]
• Hops[5]
• Hydrangea[5]
• Hydrocotyle[5]
• Juniper[5]
• Lady's slipper[5]
• Milk thistle[3]
• Motherwort[5]
• Parsley[5]
• Pilewort[5]
• Plantain[5]
• Pulsatilla[5]
• Rosemary[5]
• Tansy[5]
• Vitex agnus-castus[5]
• Wild carrot[5]
• Yarrow[5]

See also

• Alternative medicine
• Herbalism
• List of branches of alternative medicine
• List of plants used in herbalism
• List of poisonous plants

References

1. Talalay, P.; Talalay, P. (2001). "The importance of using scientific principles in the development of medicinal agents from plants". Academic Medicine. 76 (3): 238–247. doi:10.1097/00001888-200103000-00010. PMID 11242573.
2. Eisenberg, D. M. (1997). "Advising patients who seek alternative medical therapies". Annals of Internal Medicine. 127 (1): 61–69. doi:10.7326/0003-4819-127-1-199707010-00010. PMID 9214254.
3. Elvin-Lewis, M. (2001). "Should we be concerned about herbal remedies". Journal of Ethnopharmacology. 75 (2–3): 141–164. doi:10.1016/S0378-8741(00)00394-9. PMID 11297844.
4. "Dangerous Supplements: Twelve Supplements You Should Avoid". Consumer Reports Magazine. September 2010.
5. Ernst, E. (1998). "Harmless herbs? A review of the recent literature". The American Journal of Medicine. 104 (2): 170–178. doi:10.1016/S0002-9343(97)00397-5. PMID 9528737.
6. "Betel chewing causes cancer". SciDev.
7. "Aristolochia manshuriensis - Plant Finder". www.missouribotanicalgarden.org. Retrieved 6 March 2019.
8. "Natural Does Not Mean Safe". Slate Magazine. 2012.
9. "Aristolochic Acid: FDA Concerned About Botanical Products, Including Dietary Supplements, Containing Aristolochic Acid". FDA. 2001.
10. Daniele, C.; Dahamna, S.; Firuzi, O.; Sekfali, N.; Saso, L.; Mazzanti, G. (2005). "Atractylis gummifera L. Poisoning: An ethnopharmacological review". Journal of Ethnopharmacology. 97 (2): 175–181. doi:10.1016/j.jep.2004.11.025. PMID 15707749.
11. Saper, RB; Phillips, RS; Sehgal, A; Khouri, N; Davis, RB; Paquin, J; Thuppil, V; Kales, SN (27 August 2008). "Lead, mercury, and arsenic in US- and Indian-manufactured Ayurvedic medicines sold via the Internet". JAMA: The Journal of the American Medical Association. 300 (8): 915–23. doi:10.1001/jama.300.8.915. PMC 2755247. PMID 18728265.
12. "Broom". WebMD.
13. Chan, T. Y. (2001). "Interaction between warfarin and danshen (Salvia miltiorrhiza)". The Annals of Pharmacotherapy. 35 (4): 501–504. doi:10.1345/aph.19029. PMID 11302416.
14. HH, Tsai (2013). "A review of potential harmful interactions between anticoagulant/antiplatelet agents and Chinese herbal medicines". PLoS ONE. 8 (5): e64255. Bibcode:2013PLoSO...864255T. doi:10.1371/journal.pone.0064255. PMC 3650066. PMID 23671711.
15. Cupp, M. J. (1999). "Herbal remedies: Adverse effects and drug interactions". American Family Physician. 59 (5): 1239–1245. PMID 10088878.
16. "Herbal Medicine". University of Maryland Medical Center. Archived from the original on 20 December 2017. Retrieved 1 September 2018.
17. "American Ginseng". WebMD.
18. Norton, Scott A.; Ruze, Patricia (1 July 1994). "Kava dermopathy". Journal of the American Academy of Dermatology. 31 (1): 89–97. doi:10.1016/S0190-9622(94)70142-3. PMID 8021378.
19. Pantano, Flaminia; Tittarelli, Roberta; Mannocchi, Giulio; Zaami, Simona; Ricci, Serafino; Giorgetti, Raffaele; Terranova, Daniela; Busardò, Francesco; Marinelli, Enrico (16 April 2016). "Hepatotoxicity Induced by 'the 3Ks': Kava, Kratom and Khat". International Journal of Molecular Sciences. 17 (4): 580. doi:10.3390/ijms17040580. PMC 4849036. PMID 27092496.
20. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. National Institute of Diabetes and Digestive and Kidney Diseases. 2012.
21. "Peony". WebMD. Retrieved 31 December 2011.
22. "Vasambu". Tamilnadu.com. 1 April 2013. Archived from the original on 22 May 2016.
23. "Chamomile".
24. Astragalus, NCCAM
25. Heydari, Mojtaba; Mayer, Johannes Gottfried; Hashempur, Mohammad Hashem; Raee, Mohammad Javad; Ostovar, Mohadeseh; Hajimonfarednejad, Mahdie (5 April 2018). "Cinnamon: A systematic review of adverse events". Clinical Nutrition. 0 (2): 594–602. doi:10.1016/j.clnu.2018.03.013. PMID 29661513.