Quick answer
No dose of chaga has been tested in human trials, and no safe daily amount has been set. In the kidney damage reports, people took 3 to 15 g of powder, or 4 to 5 teaspoons, a day for months to years. Oxalate varied about fivefold between products tested, from 2.8 to 14.2 g per 100 g.1,2
Key facts
- At 0.14 g of oxalate per gram, 9 g of powder supplied about 1,260 mg of oxalate a day.1
- The man in the five-year case took 3 g a day because the seller recommended it, and later raised it to 9 g.1
- Water and alcohol extracts of chaga contained oxalic acid as their main organic acid.3
- In rats, kidney injury appeared at the higher of two doses tested.4
Why there is no standard dose
A dose is normally worked out from trials that compare amounts and track both effects and side effects. Chaga has none: we found no trial of chaga on its own in people, so any amount on a label is not based on trials. The man in the five-year kidney report took 3 g a day because the company that sold the powder recommended it.1
Chaga powders from three companies held 2.8 g, 11.2 g and 14.2 g of oxalate per 100 g.1
That spread matters as much as the dose. The same spoonful from two products could deliver about five times as much oxalate from one as from the other.1
Oxalate per daily amount
The table works out the oxalate in common daily amounts of powder, using the lowest and highest levels measured in that report. A typical diet already supplies 200 to 300 mg of oxalate a day.1
| Chaga powder a day | Lowest tested, 2.8 g per 100 g | Highest tested, about 14 g per 100 g |
|---|---|---|
| 1 g | 28 mg | 140 mg |
| 3 g | 84 mg | 420 mg |
| 9 g | 252 mg | 1,260 mg |
| 15 g | 420 mg | 2,100 mg |
For people prone to kidney stones, the report's authors cite a goal of under 100 mg of oxalate a day, which 1 g of the strongest powder would already pass.1
Amounts in the kidney reports
| Case | Daily amount | How long | Outcome |
|---|---|---|---|
| Woman, 72, Japan | 4 to 5 teaspoons of powder | 6 months | Needed dialysis |
| Man, 49, Korea | 3 g of powder, then 9 g | 5 years | Kidney failure, still on dialysis 18 months later |
| Man, 69, Korea | 10 to 15 g of powder, with 500 mg of vitamin C | 3 months | Recovered after dialysis and steroids |
All three took powder every day for months or longer. Whether shorter courses or smaller amounts carry risk is unknown, because we found no study of them.
In the rat study, kidney changes appeared at the higher of two doses. The lower dose had been set to match one of the human cases.4
What's in ours
Chaga's share of the blend above is not on the label. It cannot be more than the blend's total, which is under a tenth of the 3 g a day taken in the five-year case, but no amount of chaga has been shown to be safe.1
Who should not take chaga
- Anyone with kidney disease or a history of kidney stones, unless a kidney doctor agrees1
- Ask first if you take vitamin C supplements, which add to the oxalate load1,2
- Ask first if you are pregnant or breastfeeding, take a blood thinner, or take medicine that lowers blood sugar6,7
- If you already take chaga every day, tell your doctor, who may want to check your kidney function1
Questions people ask
How much chaga tea per day is safe?
No amount has been shown to be safe. Water extracts of chaga had oxalic acid as their main organic acid, but none of the studies we found measured how much oxalate a cup of chaga tea delivers.3
Is 1 g of chaga a day too much?
We found no study of it. Using the oxalate levels measured in one report, 1 g of powder would supply about 28 to 140 mg of oxalate, on top of the 200 to 300 mg in a typical diet.1
See what we make
Every product shows its whole label and what its lab report covers. The store opens soon.
Sources
- Lee S, Lee HY, Park Y, Ko EJ, Ban TH, Chung BH, Lee HS, Yang CW. Development of End Stage Renal Disease after Long-Term Ingestion of Chaga Mushroom: Case Report and Review of Literature. J Korean Med Sci. 2020;35(19):e122. Opened 2026-10-07.
- Kwon O, Kim Y, Paek JH, Park WY, Han S, Sin H, Jin K. Chaga mushroom-induced oxalate nephropathy that clinically manifested as nephrotic syndrome: A case report. Medicine (Baltimore). 2022;101(10):e28997. Opened 2026-10-07.
- Glamočlija J, Ćirić A, Nikolić M, Fernandes Â, Barros L, Calhelha RC, Ferreira IC, Soković M, van Griensven LJ. Chemical characterization and biological activity of Chaga (Inonotus obliquus), a medicinal "mushroom". J Ethnopharmacol. 2015;162:323-332. Opened 2026-10-07.
- Lee S, Cui S, Fang X, Lee H, Lim SW, Shin YJ, Li C, Yang CW, Chung BH. Kidney Injury Induced by High-Dose Chaga Mushroom Consumption: Experimental Evidence in a Rat Model. J Korean Med Sci. 2026;41(3):e37. Opened 2026-10-07.
- Kikuchi Y, Seta K, Ogawa Y, Takayama T, Nagata M, Taguchi T, Yahata K. Chaga mushroom-induced oxalate nephropathy. Clin Nephrol. 2014;81(6):440-444. Opened 2026-10-07.
- Hyun KW, Jeong SC, Lee DH, Park JS, Lee JS. Isolation and characterization of a novel platelet aggregation inhibitory peptide from the medicinal mushroom, Inonotus obliquus. Peptides. 2006;27(6):1173-1178. Opened 2026-10-07.
- Wang J, Wang C, Li S, Li W, Yuan G, Pan Y, Chen H. Anti-diabetic effects of Inonotus obliquus polysaccharides in streptozotocin-induced type 2 diabetic mice and potential mechanism via PI3K-Akt signal pathway. Biomed Pharmacother. 2017;95:1669-1677. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.