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Herb library · Mushroom · Inonotus obliquus

Chaga

A fungus that grows on birch trees, ground into powders and teas and sold for cancer and inflammation. No trial in people has tested it; the studies in people are case reports of serious kidney injury from its very high oxalate content.

Serious warning

Chaga contains extremely high levels of oxalate. Case reports in PubMed describe oxalate kidney injury in people taking chaga powder daily: a 72-year-old woman who needed dialysis after 6 months, a 49-year-old man who developed end-stage kidney disease after about 5 years, and a 69-year-old man who needed dialysis after 3 months.

Traditional use

A fungus parasitic on birch and other trees. It has been used in folk and botanical medicine for cancer, gastritis, ulcers and tuberculosis of the bones, and today it is sold as a powder, tea or extract for cancer, skin conditions and inflammation; in the reported kidney cases people were taking it for liver cancer and for eczema (atopic dermatitis).

What studies show

  • Insufficient

    Cancer and inflammation: chaga has been reported to have anti-inflammatory and antioxidant effects, but a PubMed search found no clinical trial in people for any use.

Be careful of

Cautions

  • AmountIn the reported cases people took several teaspoons (4 to 5, or 10 to 15 grams) of chaga powder a day for months. One chaga sample measured 14.2 g of oxalate per 100 g.
  • ConditionIn one case the kidney damage was permanent (end-stage kidney disease); in another, kidney function recovered only after dialysis and steroids. The authors urge clinicians to ask about chaga when kidney injury has no clear cause.
  • NoteTell your clinician you take chaga, especially if you have kidney problems.
  • Ask a clinicianTalk with a clinician or pharmacist before using this if you take prescription medicines, are pregnant or breastfeeding, or are giving it to a child.

Sources

  1. Chaga mushroom-induced oxalate nephropathy (case report, 2014) (opens in a new tab) · NIH · read September 25, 2026
  2. Development of End Stage Renal Disease after Long-Term Ingestion of Chaga Mushroom (case report, 2020) (opens in a new tab) · NIH · read September 25, 2026
  3. Chaga mushroom-induced oxalate nephropathy that clinically manifested as nephrotic syndrome (case report, 2022) (opens in a new tab) · NIH · read September 25, 2026

Reviewed September 25, 2026.