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Limited evidenceImmunity

Reishi Mushroom

Two Cochrane reviews looked hard at reishi and found little: no demonstrated survival benefit in cancer and no benefit at all for cardiovascular risk factors. Extremely popular, and the human data are poor.

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What the science says

  • Adjunct in cancer treatment Limited evidence

    A Cochrane review found 5 eligible RCTs. Patients given Ganoderma lucidum alongside chemotherapy or radiotherapy were more likely to show a tumour response (RR 1.50, 95% CI 0.90-2.51), but the confidence interval crosses no effect, no trial recorded long-term survival, and the reviewers described the methodological quality as generally unsatisfying. Cochrane did not recommend it as first-line treatment.

  • Cardiovascular risk factors and glycemia Limited evidence

    A separate Cochrane review of 5 trials in 398 participants — with the analysable trials giving 1.4-3 g/day for 12-16 weeks to people with type 2 diabetes — found no significant effect on HbA1c (WMD -0.10%), total cholesterol, LDL, BMI, blood pressure, or triglycerides. The authors' conclusion was explicit: the evidence does not support its use for cardiovascular risk factors.

  • Sleep, stress, and adaptogenic effects Limited evidence

    Reishi is widely marketed for calm and sleep on the strength of rodent studies showing sedative and sleep-latency effects. There is no adequate human randomized trial for sleep or stress outcomes.

Dosage & safety

Studied doseTrials used 1.4-3 g/day of extract, or the equivalent of roughly 1.5-9 g/day of dried mushroom, for 12-16 weeks. No dose has been established as effective for any indication. Extract-to-raw ratios and beta-glucan content vary hugely between products.
SafetyAdverse effects are usually mild — dizziness, dry mouth, nosebleed, GI upset — but in the Cochrane cardiovascular review participants on reishi were 1.67 times more likely than placebo to report an adverse event (none serious). Case reports link powdered reishi to hepatotoxicity, including a fatal case of fulminant hepatitis; the powdered form appears more implicated than hot-water extracts. Reishi has antiplatelet activity — caution with anticoagulants, antiplatelets, and before surgery. Avoid in pregnancy, breastfeeding, and alongside immunosuppressants.

How to take it

TimingTiming does not matter.
With food?Take it with food to reduce GI upset.
Worth knowingChoose hot-water extracts over raw powder - the hepatotoxicity case reports, including a fatal one, centre on powdered reishi.

Interactions

With medications

  • warfarin, DOACs and antiplatelet drugs

    Reishi has antiplatelet activity that may add to bleeding risk. tell your prescriber and stop it before surgery

  • ciclosporin, tacrolimus and other immunosuppressants

    Immune modulation theoretically opposes the drug. do not combine on immunosuppressive therapy

With other supplements

  • fish oil, garlic and ginkgo

    Additive antiplatelet effect. do not stack them around surgery

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does reishi mushroom help with cancer?

The evidence is limited: a Cochrane review of 5 trials found reishi alongside chemotherapy or radiotherapy did not show a clear tumour response benefit, and no trial recorded long-term survival. Cochrane did not recommend it as first-line treatment.

Does reishi lower blood sugar, cholesterol or blood pressure?

No: a Cochrane review of 5 trials in 398 participants found reishi had no significant effect on HbA1c, cholesterol, blood pressure or triglycerides. The authors concluded the evidence does not support its use for cardiovascular risk factors.

Does reishi help sleep or stress?

Reishi's sleep and stress claims rest on rodent studies; there is no adequate human randomised trial for these outcomes.

Is reishi safe?

Reishi side effects are usually mild, but case reports link powdered reishi to liver toxicity, including a fatal case, so hot-water extracts are preferable. Reishi has antiplatelet activity, so take care with anticoagulants, stop it before surgery, and avoid it with immunosuppressants or in pregnancy.

Scientific references

Where to buy

Swanson Vitamins, Reishi Mushroom Extract, Standardized, 500 mg, 90 Capsules

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