Supplements

Cordyceps

Updated · 28 sources · Editorial policy

Cordyceps is the name used for a group of medicinal fungi sold as dietary supplements, mainly for endurance, energy and “lung and kidney” support. The original product is the wild caterpillar fungus of the Tibetan Plateau, now classified as Ophiocordyceps sinensis. Almost everything sold today is a cultivated substitute: fermented mycelium (the root-like body of the fungus) or the related species Cordyceps militaris.

The single most important fact for athletes: controlled trials of cordyceps on endurance are small and conflicting. The best-designed early trials in trained cyclists found no effect, while a few later trials and a 2025 meta-analysis reported modest gains in aerobic markers. No randomized human trial has shown an effect on muscle mass or testosterone.

This page summarizes what clinical trials, systematic reviews and regulators report. It is for education only and is not medical advice.

Property Detail
Type Medicinal fungus; sold as a dietary supplement
Main species Ophiocordyceps sinensis (formerly Cordyceps sinensis, wild) and Cordyceps militaris (cultivated)
Common commercial form Cs-4: a fermented mycelium from a Paecilomyces hepiali strain isolated from wild O. sinensis
Route Oral (capsules, powders, extracts)
Doses in cited trials Cs-4 333 mg three times daily; CordyMax Cs-4 3 g/day; C. militaris extract 1 g single dose
Best-known compounds Cordycepin (3′-deoxyadenosine), adenosine, mannitol, polysaccharides
Half-life No human pharmacokinetic data; in rats, oral cordycepin was not absorbed intact
US status Dietary supplement; FDA does not approve supplements before marketing
WADA status Not named on the 2026 Prohibited List

What it is

Wild O. sinensis is a parasitic fungus. It infects the larvae of ghost moths (Hepialidae) living in the soil of the Qinghai-Tibetan Plateau, at around 10,000 feet. It fills the larva with mycelium and then grows a stalk out of its head. The traded product is this stalk together with the dead larva (Chen et al., J Altern Complement Med 2010).

In Chinese it is called dong chong xia cao (“winter worm, summer grass”). A 2013 systematic review noted that wild material sold for about USD 20,000–40,000 per kg. It also reported that more than 20 bioactive ingredients have been described, mainly polysaccharides, cordycepin, adenosine, mannitol and sterols (Lo et al., J Tradit Complement Med 2013).

Because wild cordyceps is scarce and costly, supplements use cultivated alternatives. These differ in what they contain, so trial results for one form do not automatically apply to another:

Form What it is Used in
Wild O. sinensis Fungus plus the larva it grew in Traditional medicine; rarely in modern trials
Cs-4 (sold as CordyMax) Standardized fermentation product of a Paecilomyces hepiali strain isolated from wild O. sinensis; specified at no less than 0.14% adenosine and 5% mannitol Parcell 2004, Earnest 2004, Chen 2010
Cordyceps militaris A separate, easily cultivated species; fruiting bodies or mycelium extracts Hirsch 2017 (in a blend), Nakamura 2024, Farzan 2026

Cordycepin was first isolated from cultures of C. militaris in 1950 (Cunningham et al., Nature 1950). Chemically it is 3′-deoxyadenosine, a close analog of the body’s own adenosine: formula C₁₀H₁₃N₅O₃, molecular weight 251.24 g/mol (PubChem).

How it works in the body

There is no agreed human mechanism for any performance effect. The proposed explanations come from animal work:

  • In rats, cultured C. sinensis mycelium at 200 mg/kg/day for 15 days increased swimming endurance and raised muscle levels of energy-regulating proteins such as AMPK and PGC-1α (Kumar et al., J Ethnopharmacol 2011). This is an animal result and has not been shown in people.
  • In mice, C. sinensis and some of its fractions raised blood testosterone and stimulated testosterone release from isolated Leydig cells (Hsu et al., Life Sci 2003). No controlled human trial has confirmed this.

Absorption and half-life

No published study has measured the half-life of cordyceps or its marker compounds in humans. In a rat study, intact cordycepin was not absorbed after oral dosing. Only its breakdown product, 3′-deoxyinosine, reached the bloodstream; in cell culture this product could be converted back into the active form of cordycepin (Lee et al., Sci Rep 2019). Any half-life figure for cordyceps supplements should therefore be treated as an estimate, not a measured value.

Regulatory status

In the US, cordyceps products are sold as dietary supplements. Under the Dietary Supplement Health and Education Act (DSHEA), FDA does not have the authority to approve dietary supplements before they are marketed. The manufacturer is responsible for making sure its product is not adulterated or misbranded (FDA).

Cordyceps is not named on the WADA 2026 Prohibited List. As with any supplement, that does not rule out contamination of a given product.

What the research shows

Endurance in trained athletes: early trials were negative

Three randomized, placebo-controlled trials in cyclists found no benefit:

Trial Participants Product and dose Duration Result
Parcell et al. 2004 22 endurance-trained male cyclists CordyMax Cs-4, 3 g/day 5 weeks No change in VO₂peak, ventilatory threshold or time-trial performance
Earnest et al. 2004 17 amateur cyclists Blend with Cs-4 (1,000 mg per 3 capsules) plus Rhodiola rosea and other ingredients 2 weeks No effect on peak VO₂, time to exhaustion or peak power
Colson et al. 2005 8 male cyclists Cordyceps plus Rhodiola formula — No effect on muscle oxygen saturation, VO₂max or time to exhaustion

In the Parcell trial, VO₂peak after supplementation was 57.1 mL/kg/min in the cordyceps group vs 60.1 mL/kg/min on placebo, and time-trial times were 62.1 vs 61.4 minutes.

A larger trial gave 96 physical education students a commercial O. sinensis plus reishi (Ganoderma lucidum) supplement at a low or high dose, or placebo, for 28–33 days. It found no effect on VO₂max, peak or mean anaerobic power, or fatigue index (Tsuk et al., Int J Med Mushrooms 2018).

Endurance: later positive trials

Trial Participants Product and dose Duration Main result
Chen et al. 2010 20 healthy adults aged 50–75 Cs-4 333 mg three times daily 12 weeks Metabolic threshold +10.5% (p under 0.02); ventilatory threshold +8.5%; no change in VO₂max
Hirsch et al. 2017 28 young adults (10 continued to week 3) 4 g/day blend of C. militaris, five other mushrooms and hemp protein 1 and 3 weeks No significant group-by-time effects at 1 week; at 3 weeks VO₂max +4.8 vs +0.9 mL/kg/min on placebo (p = 0.042)
Farzan & Koushkie Jahromi 2026 12 recreationally active men (crossover) 1 g C. militaris extract, single dose Acute No change in peak VO₂; faster post-exercise reaction time

Each of these is small. The Hirsch result came from a 10-person subgroup taking a six-mushroom blend, so it cannot be attributed to cordyceps alone. The other mushrooms included reishi and lion’s mane.

What the meta-analysis found

A 2025 systematic review identified 14 randomized trials of fungal supplements in 528 athletes; 8 trials (n = 288) were pooled (Shu et al., Front Nutr 2025). For C. sinensis vs placebo it reported:

Outcome Result
Endurance performance Borderline improvement (p = 0.05; pooled from 2 studies)
Ventilatory threshold Improved (p = 0.03)
VO₂peak Improved (p = 0.04)

The authors noted that the products varied widely in extraction method and strength, and that most included trials had “some concerns” for bias. A 2026 review of the five human C. militaris trials (321 participants) reached a similar view. It found some improvements, but called the findings “inconsistent” and limited by small samples, mixed products and lack of trial registration (Jędrejko et al., Nutrients 2026).

Muscle recovery and blood markers

  • Muscle damage after intense exercise. In a crossover trial in 14 young adults, 1 g of C. sinensis before high-intensity cycling reduced the rise in damaged-cell infiltration in thigh-muscle biopsies. It also moved the rise in CD34+ stem cells from 24 hours to 3 hours after exercise (+51%, p = 0.002) (Dewi et al., Food Funct 2024). This is a tissue-level finding; the trial did not measure strength or performance.
  • Iron and red cells in runners. In a 16-week double-blind trial in 22 long-distance runners, a C. militaris mycelium extract maintained serum ferritin, hemoglobin and hematocrit better than placebo at some time points. Creatine kinase, a marker of muscle damage, was lower at week 16 (Nakamura et al., Nutrients 2024). The study was funded by the supplement’s maker.

Muscle mass and testosterone

No randomized human trial has shown that cordyceps increases lean mass, strength or testosterone. The testosterone claims rest on mouse and cell studies (Hsu et al. 2003).

Kidney disease

Kidney disease is the area with the most clinical trials, which tested cordyceps preparations alongside standard treatment.

A Cochrane review pooled 22 studies with 1,746 people with chronic kidney disease (Zhang et al., Cochrane 2014). In people not on dialysis:

Outcome Effect of cordyceps vs control
Serum creatinine (14 studies, 987 people) −60.76 μmol/L, ≈ −0.69 mg/dL (95% CI −85.82 to −35.71 μmol/L)
Creatinine clearance (6 studies, 362 people) +9.22 mL/min (95% CI 3.10–15.34)
24-hour proteinuria (4 studies, 211 people) −0.15 g/24 h (95% CI −0.24 to −0.05)

Risk of bias was high in 4 studies and unclear in 18. The authors concluded that definitive conclusions could not be drawn because the evidence was of low quality.

A second Cochrane review covered 5 studies (447 kidney transplant recipients) in which cordyceps was used as an add-on to immunosuppressive drugs. Compared with azathioprine, it showed no difference in graft or patient survival. All studies had an unclear risk of bias (Hong et al., Cochrane 2015).

Side effects and risks

Tolerability in trials

Short trials have reported few side effects. In the 12-week Cs-4 trial in older adults, no adverse events occurred (Chen et al. 2010). However, the 2025 meta-analysis found that only 3 of its 14 trials mentioned adverse events at all, and none collected them systematically (Shu et al. 2025). Long-term safety data are lacking.

Reported case reports

Case reports cannot prove cause, but they show what has been linked to cordyceps:

Prostate cancer (animal data)

In mice, C. sinensis raised serum testosterone and enlarged the prostate. It also doubled the viability of androgen-sensitive prostate cancer cells in culture and raised PSA in mice carrying human prostate tumors (Ma et al., Nutr Cancer 2018). These are animal and cell findings only. The authors called for further study of whether cordyceps is safe for people with prostate cancer.

Transplant and immune-suppressing drugs

In Chinese transplant practice, cordyceps has been studied as an add-on immunosuppressive agent (Hong et al., Cochrane 2015). That use implies effects on the immune system. The review called for studies combining cordyceps with tacrolimus, mycophenolate mofetil and other current transplant drugs, which had not yet been done.

Quality and contamination

  • Lead. Two people developed lead poisoning from cordyceps powder that contained up to 20,000 ppm lead. Blood lead levels were 130 and 46 μg/dL, and returned to normal after they stopped (one also needed chelation) (Wu et al., Sci Total Environ 1996).
  • Arsenic. Testing for arsenic has become a required check for O. sinensis, to confirm that inorganic arsenic is under the set limit (Guo et al., Molecules 2018). A 2025 study found no liver or kidney toxicity in mice given wild cordyceps at the maximum clinical dose, unlike an equal dose of inorganic arsenic (Gao et al., Front Pharmacol 2025). This is a mouse study.
  • Product identity. Because wild cordyceps is so expensive, adulteration of processed products is common (Guo et al. 2018). Most supplements are cultivated mycelium or C. militaris, which differ chemically from the wild fungus.

Key takeaways

  • Several different products share one name. Wild O. sinensis, Cs-4 fermented mycelium and C. militaris are not interchangeable, and trial results for one do not transfer automatically.
  • Endurance evidence is mixed. The early cyclist trials were negative. Later small trials and a 2025 meta-analysis report modest gains in ventilatory threshold and VO₂peak, with low-quality evidence.
  • No anabolic effect shown in people. Testosterone and muscle claims come from mouse and cell studies only.
  • Kidney data are the most extensive but weak. Cochrane found lower creatinine in chronic kidney disease, but in trials judged at high or unclear risk of bias.
  • Generally well tolerated in short trials, with caveats. Case reports describe bleeding, allergy and liver vessel disease, and contaminated products have caused lead poisoning.
  • No human pharmacokinetic data. In rats, cordycepin is not absorbed intact, so published “half-life” figures for cordyceps are not based on human measurement.

Sources

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  9. World Anti-Doping Agency. The 2026 Prohibited List. WADA 2026 Prohibited List.
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