Are These 40 Herbs Dangerous? Adverse Effects Reported!

Plants are my medicine presents (1)

It is the common misbelief that just because a plant or herb is natural, that it is safe. This couldn’t be further from the truth. Each herb has contraindications and warnings associated with it. Browse this list and understand that not every herb is safe for everyone. If you want to use herbal remedies, enroll in a course that teaches you the synergy and contraindications of herbs.

We want everyone to be safe, happy, and of course healthy. This list is to educate you, not scare you. If you find that you use one of these herbs on a regular basis, ask your herbalist to help you find a plant remedy that is more suitable for your needs. If you are the DIY’er, check my list of recommended reading after the list.

  1. Aconite: Heart palpitations and arrhythmias, hypotension, nausea, vomiting, abdominal pain, respiratory system paralysis, death.
  2. Aloe Vera: abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents
  3. Areca Nut (Betel Nut): deterioration of psychosis in patients with preexisting psychiatric disorders”; known carcinogen contributing to cancer of the mouth, pharynx, esophagus and stomach when chewed.
  4. Bitter Orange: ‘Fainting, arrhythmia, heart attack, stroke, death.
  5. Broom: Uterotonic properties, nausea vomiting, and diarrhea, contraindicated for pregnancy and breast feeding
  6. Buckthorn Bark and Berry: abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents
  7. Cascara Sagrada Bark: “abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents
  8. Chaparral: Liver damage, kidney problems, Hypotension in cancer patients
  9. Coltsfoot: Liver damage, cancer
  10. Comfrey: Liver damage and cancer
  11. Country Mallow: Heart attack, heart arrhythmia, stroke, death
  12. Dan Shen: Potentiates warfarin activity, leading to excessive anticoagulation and bleeding
  13. Dong Quai: May induce uterine contractions; contraindicated when pregnant or nursing
  14. European Mistletoe: Toxic to cardio and central nervous systems, gastrointestinal bleeding
  15. Ephedra: Agitation and palpitations, “hypertension, irregular heart rate, insomnia, nervousness, tremors and seizures, paranoid psychoses, heart attacks, strokes, and death”, kidney stones
  16. Germander: Liver damage
  17. Ginger: May alter bleeding time
  18. Gingko: Bleeding
  19. American Ginseng: Hypertensive and chronotropic activities, may increase digoxin levels”, 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. May lower blood sugar excessively in combination with diabetes medication. Contains a chemical linked to possible birth defects. May worsen hormone sensitive conditions such as breast cancer, uterine cancer, ovarian cancer, endometriosis, and uterine fibroids. Insomnia.
  20. Goldenseal: Uterotonic
  21. Greater Celandine: Liver damage
  22. Guarana: Agitation and insomnia
  23. Guar Gum: Obstruction of gastrointestinal tract
  24. Gugulipid (myrrh and guggal): Headache, nausea, hiccups, diminished efficacy of other cardiovascular drugs including diltiazem and propranolol.
  25. Hawthorn: Potentiates digitalis activity, increases coronary dilation effects of theophylline, caffeine, papaverine, sodium nitrate, adenosine and epinephrine, increase barbiturate-induced sleeping times.
  26. Horse Chestnut: Liver toxicity, allergic reaction, anaphylaxis
  27. Kava: Potentates CNS sedatives, chronic use might cause a reversible dry skin condition
  28. Khat: Chronic liver dysfunction
  29. Licorice Root: Hypokalemia, hypertension, arrhythmias, edema
  30. Lobelia: Toxicity, rapid heartbeat, hypotension, coma, death
  31. Milk Thistle: Mild laxative, allergy
  32. Pennyroyal: Liver damage
  33. Peony: May slow clotting; contraindicated for people with bleeding disorders and before and after surgery. May induce uterine contractions; contraindicated when pregnant or nursing.
  34. Safrole (sassafras): Liver damage
  35. Saw Palmetto: “rare and mild gastrointestinal upset, headaches, diarrhea, gynecomastia, paroxysmal atrial fibrillation, ventricular rupture and death in one patient.
  36. Senna: “abdominal pain, diarrhea, potentially carcinogenic, with others can potentiate cardiac glycosides and antiarrhythmic agents”, liver damage.
  37. St. John’s Wort: Photosensitization, GI disturbances, “allergic reactions, fatigue, dizziness, confusion, dry mouth
  38. Valerian: “drowsiness, GI upset, headache, palpitations, insomnia”, oversedation, overstimulation
  39. Vasambu: Vomiting and nausea
  40. Yohimbe: rapid heart rate, hypertension, hypotension, heart problems, death

Plants Are My Medicine Presents-

My Recommended Reading List:

The Essential Guide to Herbal Safety
The Way of Herbs
Botanical Safety Handbook

Learn Herbs
Tea, Infusion, & Juice Recipes (my ebook on Kindle, free to unlimited subscribers)

Learn more about herbs and their actions in our Beginner’s herbal course for only $65 (Introductory Price)!


  1.  Talalay, P.; Talalay, P. (2001). “The importance of using scientific principles in the development of medicinal agents from plants”. Academic Medicine76 (3): 238–247. PMID 11242573doi:10.1097/00001888-200103000-00010.
  2.  Eisenberg, D. M. (1997). “Advising patients who seek alternative medical therapies”. Annals of Internal Medicine127 (1): 61–69. PMID 9214254doi:10.7326/0003-4819-127-1-199707010-00010.
  3. Elvin-Lewis, M. (2001). “Should we be concerned about herbal remedies”. Journal of Ethnopharmacology75 (2–3): 141–164. PMID 11297844doi:10.1016/S0378-8741(00)00394-9.
  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 Medicine104 (2): 170–178. PMID 9528737doi:10.1016/S0002-9343(97)00397-5.
  6.  “Betel chewing causes cancer”. SciDev.
  7.  “Natural Does Not Mean Safe”. Slate Magazine. 2012.
  8. “Aristolochic Acid: FDA Concerned About Botanical Products, Including Dietary Supplements, Containing Aristolochic Acid”. FDA. 2001.
  9. Daniele, C.; Dahamna, S.; Firuzi, O.; Sekfali, N.; Saso, L.; Mazzanti, G. (2005). “Atractylis gummifera L. Poisoning: An ethnopharmacological review”. Journal of Ethnopharmacology97(2): 175–181. PMID 15707749doi:10.1016/j.jep.2004.11.025.
  10. 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 Association300 (8): 915–23. PMC 2755247Freely accessiblePMID 18728265doi:10.1001/jama.300.8.915.
  11. “Broom”. WebMD.
  12. Chan, T. Y. (2001). “Interaction between warfarin and danshen (Salvia miltiorrhiza)”. The Annals of Pharmacotherapy35 (4): 501–504. PMID 11302416doi:10.1345/aph.19029.
  13. HH, Tsai (2013). “A review of potential harmful interactions between anticoagulant/antiplatelet agents and Chinese herbal medicines”PLoS ONE8 (5): e64255. Bibcode:2013PLoSO…864255TPMC 3650066Freely accessiblePMID 23671711doi:10.1371/journal.pone.0064255.
  14. Cupp, M. J. (1999). “Herbal remedies: Adverse effects and drug interactions”American Family Physician59 (5): 1239–1245. PMID 10088878.
  15. “Herbal Medicine”. University of Maryland Medical Center.
  16. “American Ginseng”. WebMD.
  17. Norton, Scott A.; Ruze, Patricia (1994-07-01). “Kava dermopathy”Journal of the American Academy of Dermatology31 (1): 89–97. PMID 8021378doi:10.1016/S0190-9622(94)70142-3.
  18.  “Peony”. WebMD. Retrieved 2011-12-31.
  19.  “Vasambu”. 1 April 2013. Archived from the original on 22 May 2016.

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