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Research · Supplements

Cordyceps

A meta-analysis of athlete trials reports small gains in VO2 peak and endurance with Cordyceps sinensis, at borderline significance. Individual trials disagree, and a trial in trained cyclists found no change. Two kidney reviews report lower creatinine from low-quality trials. Wild Cordyceps sinensis contains arsenic, measured at 5.77 to 13.20 µg/g.

Add to Bio HackChecked 2026-11-09
Status
Dietary supplement in the US. Not approved by the FDA as a drug for any use.
Also called
Cordyceps sinensis, Ophiocordyceps sinensis, Cordyceps militaris, caterpillar fungus, dong chong xia cao, yartsa gunbu, Cs-4, CordyMax, cordycepin
Taken for
endurance, VO2 max, energy, exercise performance, immunity, kidney health, libido, stamina

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help2

Reported risks1

What people take it for, and what was found

Shown to help2

LimitedStudied in men

Immune markers

One trial found 1.5 g a day raised natural killer cell activity and other immune markers in 79 healthy men. Infections were not measured.

The numbers and sources
Effect
In 79 healthy Korean men, 1.5 g a day of Cordyceps militaris for 4 weeks raised natural killer cell activity, lymphocyte proliferation, IL-2 and interferon gamma more than placebo [5].
Population
79 healthy men [5].
Sources
[5]
Caveats
Blood markers, not infection rates. One trial.
Moderate

Kidney function

Shown to lower serum creatinine and urine protein when added to treatment in chronic kidney disease, in low-quality trials.

The numbers and sources
Effect
In a Cochrane review of 22 studies (1,746 participants), Cordyceps preparations added to conventional treatment lowered serum creatinine by 60.76 µmol/L (14 studies), raised creatinine clearance by 9.22 mL/min (6 studies) and cut 24-hour proteinuria by 0.15 g (4 studies) in people not on dialysis [6]. A 2025 meta-analysis of 15 studies (1,310 patients) with kidney dysfunction, including acute kidney injury, found Cordyceps sinensis as an add-on lowered blood creatinine, shortened the period of low urine output and raised urine osmolality [7].
Population
People with chronic kidney disease [6]; people with kidney dysfunction, including acute kidney injury [7].
Sources
[6], [7]
Caveats
Both reviews rest on low-quality trials. Risk of bias was high in 4 studies and unclear in 18, and the Cochrane authors could not reach definitive conclusions [6]. The 2025 review reported overall efficacy as diagnostic accuracy statistics, gives no size for the creatinine change in its abstract, and found results differed between northern and southern Chinese patients [7].

Mixed results1

Limited

Endurance and aerobic capacity

Small trials found mixed results: one review found better endurance in athletes, while trained cyclists showed no change and older adults gained in thresholds only.

The numbers and sources
Effect
In a meta-analysis of fungal supplements in athletes (14 RCTs, 528 athletes, 8 pooled), Cordyceps sinensis improved endurance (p 0.05), ventilatory threshold (p 0.03) and VO2 peak (p 0.04) [1]. In 22 trained male cyclists, 3 g a day of CordyMax Cs-4 for 5 weeks did not change VO2 peak, ventilatory threshold or time trial results [2]. In 20 adults aged 50 to 75, Cs-4 for 12 weeks raised metabolic threshold 10.5% and ventilatory threshold 8.5%, and VO2 max did not change [3]. In 28 young adults, a mushroom blend with Cordyceps militaris showed no change after 1 week, and in the 10 who continued for 3 weeks VO2 max rose 4.8 mL/kg/min [4].
Population
Athletes [1], trained cyclists [2], healthy older adults [3], young adults [4].
Sources
[1], [2], [3], [4]
Caveats
Trials are small and disagree. The meta-analysis abstract gives p-values without effect sizes, and its search included a Chinese database [1]. Trial [4] tested a blend, not cordyceps alone.

Claimed, not studied in people1

Untested

Libido and sexual function

Not studied in people. In diabetic male rats, Cordyceps militaris improved mating behavior and testosterone, and Cordyceps sinensis raised testosterone in mice.

No study in people. This rests on animal studies, lab studies.

The numbers and sources
Effect
In male rats made diabetic with streptozotocin, 21 days of Cordyceps militaris improved sperm measures, serum testosterone and copulatory behavior compared with untreated diabetic rats [10]. Cordyceps sinensis and two of its extracted fractions raised testosterone production in isolated mouse Leydig cells and raised plasma testosterone in live mice [11].
Population
Wistar rats, healthy and diabetic [10]. Mice and mouse Leydig cells [11].
Sources
[10], [11]
Caveats
Animal and cell findings do not show an effect on desire or sexual function in people. No human trial of Cordyceps for libido was located in Europe PMC.

Doses studied

Exercise trials used 3 g a day of Cs-4 for 5 weeks [2], 333 mg three times a day for 12 weeks [3], and 4 g a day of a mushroom blend for 1 to 3 weeks [4]. The immune trial used 1.5 g a day for 4 weeks [5].

Risks

Reported risks1

LimitedHow often is not known

Arsenic in wild Cordyceps sinensis

Limited evidence: wild Cordyceps sinensis samples from China contained 5.77 to 13.20 µg/g of arsenic, partly inorganic.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
Total arsenic in wild Cordyceps sinensis samples ranged from 5.77 to 13.20 µg/g, averaging 8.85 µg/g. Inorganic arsenic made up 4.47% to 11.42% of extracted arsenic [8]. A second analysis found an unknown arsenic species that may convert to free inorganic arsenic, and its risk assessment indicated potential health risks [9].
Population
Wild Cordyceps sinensis samples [8][9].
Sources
[8], [9]
Caveats
Both studies tested wild material from China. They do not report levels in cultivated Cordyceps militaris or in US supplements.

Checked, no increase found1

LimitedStudied in men

Adverse reactions in trials

One short trial found adverse reactions about as common on cordyceps as on placebo in 79 healthy men.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
In the 4-week immune trial, adverse reactions did not differ significantly from placebo [5].
Population
79 healthy men [5].
Sources
[5]
Caveats
One short trial. The kidney review rated most of its studies at unclear risk of bias, so harms in those trials are uncertain [6].

Claims tested and not found

  1. That Cordyceps raises VO2 peak or endurance in trained athletes. In 22 trained cyclists, 5 weeks of Cs-4 did not change VO2 peak, ventilatory threshold or time trial performance [2].
  2. That Cordyceps raises VO2 max in older adults. VO2 max did not change in either group after 12 weeks [3].

Sources

  1. Shu MY, Zhang XC, Zuo L, et al. Effects of fungal supplementation on endurance, immune function, and hematological profiles in adult athletes: a systematic review and meta-analysis. Frontiers in Nutrition. 2025. https://doi.org/10.3389/fnut.2025.1670416
  2. Parcell AC, Smith JM, Schulthies SS, et al. Cordyceps Sinensis (CordyMax Cs-4) Supplementation Does Not Improve Endurance Exercise Performance. International Journal of Sport Nutrition and Exercise Metabolism. 2004. https://doi.org/10.1123/ijsnem.14.2.236
  3. Chen S, Li Z, Krochmal R, et al. Effect of Cs-4 (Cordyceps sinensis) on Exercise Performance in Healthy Older Subjects: A Double-Blind, Placebo-Controlled Trial. The Journal of Alternative and Complementary Medicine. 2010. https://doi.org/10.1089/acm.2009.0226
  4. Hirsch KR, Smith-Ryan AE, Roelofs EJ, et al. Cordyceps militaris Improves Tolerance to High-Intensity Exercise After Acute and Chronic Supplementation. Journal of Dietary Supplements. 2017. https://doi.org/10.1080/19390211.2016.1203386
  5. Kang HJ, Baik HW, Kim SJ, et al. Cordyceps militaris Enhances Cell-Mediated Immunity in Healthy Korean Men. Journal of Medicinal Food. 2015. https://doi.org/10.1089/jmf.2014.3350
  6. Zhang HW, Lin ZX, Tung YS, et al. Cordyceps sinensis (a traditional Chinese medicine) for treating chronic kidney disease. Cochrane Database of Systematic Reviews. 2014. https://doi.org/10.1002/14651858.CD008353.pub2
  7. Wu F, Xu C, Si X, et al. Efficacy of traditional Chinese medicine Cordyceps sinensis as an adjunctive treatment in patients with renal dysfunction: a systematic-review and meta-analysis. Frontiers in Medicine. 2025. https://doi.org/10.3389/fmed.2024.1477569
  8. Xiao Y, Li C, Xu W, et al. Arsenic Content, Speciation, and Distribution in Wild Cordyceps sinensis. Evidence-Based Complementary and Alternative Medicine. 2021. https://doi.org/10.1155/2021/6651498
  9. Li Y, Liu Y, Han X, et al. Arsenic Species in Cordyceps sinensis and Its Potential Health Risks. Frontiers in Pharmacology. 2019. https://doi.org/10.3389/fphar.2019.01471
  10. Nguyen TV, Chumnanpuen P, Parunyakul K, et al. A study of the aphrodisiac properties of Cordyceps militaris in streptozotocin-induced diabetic male rats. Veterinary World. 2021. https://doi.org/10.14202/vetworld.2021.537-544
  11. Hsu CC, Huang YL, Tsai SJ, et al. In vivo and in vitro stimulatory effects of Cordyceps sinensis on testosterone production in mouse Leydig cells. Life Sciences. 2003. https://doi.org/10.1016/s0024-3205(03)00595-2

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