The 10 Most Dangerous Supplements (Still Legally Sold)

Documented liver failure. Irreversible kidney damage. An IARC Group 1 human carcinogen. A mushroom now sold in TikTok gummies. The 10 lowest-scoring supplements in our database all share one thing: a body count. Several are still on U.S. shelves through DSHEA loopholes.

1. Greater celandine (Chelidonium majus) — Score 22/100, the lowest in the database. 50+ documented hepatitis cases including transplants. Pulled in Germany (BfArM) in 2008.
2. Aristolochic acid — IARC Group 1 carcinogen. Causes "Chinese herb nephropathy" — irreversible kidney failure plus upper urinary-tract cancer at low cumulative doses.
3. Usnic acid — Acute liver failure, multiple transplants, at least one death traced to LipoKinetix. FDA warning since 2001 — still appears in fat-burners.
4. Calomel (mercurous chloride) — A mercury compound. Irreversible kidney and central nervous system damage. Still surfaces in "detox" products online.
5. Comfrey (oral) — Pyrrolizidine alkaloids cause hepatic veno-occlusive disease. FDA, EMA, and TGA all advise against any oral use.
6. Cesium chloride — Marketed as an alkaline "cancer cure." Multiple deaths from torsades de pointes. FDA compounding warning issued in 2018.
7. Germander — Banned in France since 1992 after at least 26 cases of liver injury, including one death from a popular slimming product.
8. Chaparral (Larrea tridentata) — FDA's adverse event registry has logged hepatitis, fulminant liver failure, and a death tied to chaparral teas.
9. Pennyroyal oil — Pulegone is a potent hepatotoxin. Fatalities from as little as 10 mL ingested as a "natural abortifacient." It is neither.
10. Amanita muscaria — The red-and-white fairytale mushroom, now sold as TikTok "microdose" gummies. Muscimol and ibotenic acid produce delirium, seizures, coma at higher doses.

Bottom line

"Natural" doesn't mean inert, and "legal" doesn't mean safe. DSHEA puts the burden on the FDA to prove harm after a product is on shelves — which means several of the supplements above remain legally available in the U.S. despite documented deaths.

See the full ranking with regulatory history and toxicity citations on Discover →