Tribulus terrestris L. · herb
Evidence tier: insufficient
A traditional Ayurvedic and TCM herb for libido, fertility, and mild testosterone support.
Claimed, not demonstrated. The steroidal saponins, chiefly protodioscin, are proposed to raise luteinising hormone and thereby testosterone. This is an animal model mechanism. The human trials that tested its endpoint, serum testosterone, overwhelmingly found no change, so the mechanism should be reported as a hypothesis that the clinical evidence has already failed to confirm rather than as an explanation for an effect. Note the compound irony that one of tribulus's own saponins is diosgenin, the same molecule behind the wild yam progesterone myth, and it does not become a hormone in the body there either.
Insufficient, and the flagship claim is not merely unproven but actively refuted. Tribulus is sold on testosterone. It does not raise testosterone. The 2025 systematic review of clinical trials in men (Nutrients, PMID 40219032) concludes in its own words that no robust evidence was found for increasing testosterone levels: eight of ten trials reported no significant change in the androgen profile, and the two that did found intra group rises of only 60 to 70 ng/dL, described by the reviewers as of low clinical magnitude, in men who were already hypogonadal. NIH LiverTox says the same thing from the other direction: studies in animal models suggested that tribulus increases testosterone levels in males and estrogen levels in females, but these hormonal effects have not been reproduced consistently in humans. The animal work is where the marketing came from, and it did not survive the jump to people. The secondary claim, sexual function, is thin and contradictory. The 2025 review found erectile dysfunction improved in three of the five trials that measured it, at 400 to 750 mg daily for one to three months, but graded this a LOW level of evidence. LiverTox is blunter still: improvements in sexual function were no greater with Tribulus terrestris extracts than with placebo. Two authorities, two different verdicts on a weak signal, is the definition of insufficient. Nothing here supports libido, fertility or athletic performance in humans. Safety is not a formality. LiverTox assigns likelihood score E*, an unproven but possible rare cause of clinically apparent liver injury at high doses or in people with existing liver disease, and the case literature is worse than that score sounds: a 2024 ACG case report (PMID 38328764) describes a 46 year old man on daily tribulus for two months admitted with total bilirubin of 48 mg/dL and creatinine of 7.1, with a biopsy consistent with drug induced liver injury, and a 2010 report (PMID 20667992) describes severe nephrotoxicity in a young healthy male. In grazing animals, tribulus causes a jaundice and photosensitivity syndrome called geeldikkop, with crystals in the bile ducts and renal tubules. An ingredient that does not do the one thing it is sold for, and that has put healthy people in hospital with combined liver and kidney injury, is a poor trade.
No regulatory dose exists. LiverTox records supplement practice as 250 to 750 mg daily. The clinical trials reviewed in 2025 used 400 to 750 mg daily for one to three months, and at those doses did not raise testosterone. There is no dose at which the testosterone claim has been shown to work, so a dose range should not be presented as a route to that outcome.
500 to 1500 mg standardised extract daily with food.
Avoid in hormone sensitive conditions. May worsen sleep apnoea in some men.
Pregnancy: avoid
Breastfeeding: avoid
Active compounds: steroidal saponins (protodioscin, dioscin, diosgenin)
Remedies using Tribulus · Browse by body system · Check it against what you take
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.