Research dossier
Clinical research on Tribulus terrestris
7 trials reviewed across 3 indications.
Strongest evidence
Sexual function & libido
Mechanism
Possibly a nitric-oxide / smooth-muscle effect on genital blood flow rather than a hormonal one — notably, the male ED trial showed improved erectile function while testosterone slightly fell, so the effect is androgen-independent.
The one genuine signal. A 12-week RCT (n=180) found Tribestan® improved erectile-function scores despite a small DROP in testosterone, and a smaller RCT (n=60) improved female sexual-desire scores. Real but limited: the best male trial is manufacturer-funded, both rely on subjective questionnaires, and the effect is modest.
A modest libido/sexual-function effect that does NOT depend on raising testosterone. Best male evidence is industry-funded; female evidence is small and short. Promising, not established.
Trials cited
Tribestan® for male erectile dysfunction (RCT)
positive · RCT
Kamenov et al., 2017, Maturitasn=180Industry-fundedThe strongest male trial: 180 men, 12 weeks. The Tribestan group improved IIEF erectile-function scores significantly more than placebo (+2.7 points, p<0.0001). Crucially, total and free testosterone actually DECLINED slightly in the active group — so any sexual-function benefit happened despite, not because of, testosterone.
Funded with involvement from Sopharma, the manufacturer of Tribestan® (an author was affiliated with its medical/regulatory department). The result is the best evidence for a sexual-function effect, but industry funding and the testosterone-independent mechanism both warrant caution.
Tribulus for female sexual dysfunction (RCT)
positive · RCT
Akhtari et al., 2014, DARU Journal of Pharmaceutical Sciencesn=60In 60 women with low sexual desire, 4 weeks of Tribulus extract significantly improved total FSFI plus the desire, arousal, lubrication, satisfaction, and pain subscales versus placebo (desire p<0.001). Side-effect rates matched placebo. Supports a libido/sexual-function effect that, as in men, does not depend on raising androgens.
Small (n=60), short (4 weeks), single-center, and using a subjective questionnaire prone to expectancy effects. A real but preliminary signal for female desire.
Testosterone & androgen support
Mechanism
Marketing proposes that steroidal saponins (chiefly protodioscin) raise luteinizing hormone and downstream testosterone. This mechanism is asserted from animal and in-vitro work and has not held up in controlled human trials.
This is the claim Tribulus is sold on, and it is not supported. A direct RCT in young men (Neychev 2005), an athlete RCT (Rogerson 2007), and an anti-doping study (Saudan 2008) all found no effect on testosterone, androstenedione, LH, or the T/E ratio. A review of athlete use reached the same conclusion. Tribulus does not raise testosterone in men.
No human evidence that Tribulus raises testosterone in eugonadal men. Animal-study claims do not translate. Treat 'natural test booster' marketing as false.
Tribulus and androgen production in young men
Null · RCT
Neychev & Mitev, 2005, Journal of Ethnopharmacologyn=21The cleanest test of the core claim. Neither 10 nor 20 mg/kg/day of Tribulus extract changed serum testosterone, androstenedione, or luteinizing hormone versus placebo in young men over 4 weeks. The 'aphrodisiac herb' did not influence androgen production at all.
Small (n=21) and short, but directly refutes the testosterone-boosting premise in exactly the demographic (young men) the supplements are marketed to.
Tribulus, strength and body composition in rugby players
Null · RCT
Rogerson et al., 2007, Journal of Strength and Conditioning Researchn=22Across 5 weeks of supervised preseason training, Tribulus produced no greater gains in strength or body composition than placebo, and did not alter the urinary testosterone/epitestosterone ratio. A direct null for the 'natural anabolic for athletes' positioning.
Both groups were training hard, so training itself drove the gains. The point stands: adding Tribulus added nothing measurable.
Tribulus and endogenous steroid doping markers
Null · Pilot
Saudan et al., 2008, Forensic Science Internationaln=2An anti-doping lab tested whether Tribulus could explain abnormal steroid profiles athletes had blamed on it. It couldn't: short-term Tribulus had no impact on endogenous testosterone metabolism or the T/E ratio. Independent confirmation, from a forensic context, that Tribulus does not shift androgen output.
Very small forensic case-investigation (n=2). Notable precisely because it was designed to give Tribulus a chance to look androgenic — and it didn't.
Tribulus supplements used by athletes (review)
negative · Systematic review
Pokrywka et al., 2014, Journal of Human KineticsThis review concluded Tribulus extract used alone does not improve androgenic status or physical performance in athletes. It also flagged two real-world problems: saponin/protodioscin content is unstable and varies by climate and region, and banned anabolic steroids have been detected in Tribulus products not declared on the label. The Australian Institute of Sport classifies it as high-risk-of-contamination.
A narrative review rather than a pooled meta-analysis, but it aligns with every controlled trial: no androgen or performance effect, plus a genuine adulteration risk.
Strength & body composition
Mechanism
Hypothesized via the (unsupported) testosterone-raising claim feeding lean mass and strength.
No support. The one controlled athlete trial (Rogerson 2007) found no greater strength or body-composition gains than placebo over 5 weeks of training. With the testosterone premise debunked, there is no mechanism left for an ergogenic effect.
No evidence of strength, muscle, or performance benefit. Ergogenic claims are unfounded — and athletes face a real product-contamination risk.
Tribulus, strength and body composition in rugby players
Null · RCT
Rogerson et al., 2007, Journal of Strength and Conditioning Researchn=22Across 5 weeks of supervised preseason training, Tribulus produced no greater gains in strength or body composition than placebo, and did not alter the urinary testosterone/epitestosterone ratio. A direct null for the 'natural anabolic for athletes' positioning.
Both groups were training hard, so training itself drove the gains. The point stands: adding Tribulus added nothing measurable.
3 forms of Tribulus terrestris compared
Standardized saponin extract
Variable — saponin/protodioscin content differs widely by source, climate, and plant part
Best forSexual function (the only indication with positive RCTs)Products are usually standardized to a saponin percentage (commonly 40–60%), but the active protodioscin fraction is unstable across batches and regions. A '90% saponins' label says little about protodioscin content. Fruit vs root vs leaf material also differ.
Tribestan®
Tribestan® standardized extract
Standardized to ≥112.5 mg furostanol saponins per 750 mg/day
Best forThe extract used in the strongest male sexual-function RCTMade by Sopharma. It is the most-studied defined Tribulus material and the form behind the positive ED trial — but that trial was manufacturer-involved, so the evidence is both the best available and the least independent.
Raw Tribulus powder (unstandardized)
Unknown and inconsistent — no defined protodioscin content
Best forCheap bulk powder; not the form studiedUnstandardized powder has unverified active content and is the category most associated with adulteration — banned anabolic steroids have been detected in athlete-marketed Tribulus products not declared on the label.
Side effects and drug interactions
Side effects
GI upset
Common
Mild nausea, stomach cramps, or reflux, generally dose-related and the most commonly reported complaint.
Hepato-, nephro-, and neurotoxicity (high dose / adulterated product)
Severe
A case report documented seizure, liver-enzyme elevation, and acute kidney injury after concentrated Tribulus intake. NIH LiverTox rates the herb only a possible RARE cause of liver injury and notes some reported cases are more plausibly explained by undisclosed anabolic-steroid use or product adulteration than by Tribulus itself.
Worse with:tribulus terrestris powder
Gentler:tribestan, tribulus terrestris extract
Adulteration with banned anabolic steroids
Severe
Not an effect of the herb but of poor sourcing: surveys found undeclared anabolic steroids in athlete-marketed Tribulus products. This both explains some 'androgenic' user reports and creates a real doping and health risk.
Worse with:tribulus terrestris powder
Gentler:tribestan
Drug interactions
Additive effect
antidiabetic drugs (insulin, sulfonylureas)antihypertensivesAnimal and limited human data suggest possible glucose- and blood-pressure-lowering effects that could be additive with medication.
Monitor blood glucose and blood pressure if combining; the human evidence is limited, so this is precautionary.
Other
lithiumhormone-sensitive conditionsPossible diuretic effect could alter lithium clearance; any genuine hormonal activity is theoretically unwanted in hormone-sensitive conditions.
Discuss with a clinician before use if you take lithium or have a hormone-sensitive condition.
Other critical caveats
- Tribulus does NOT raise testosterone in men. A direct RCT in young men (Neychev 2005), an athlete RCT (Rogerson 2007), and an anti-doping study (Saudan 2008) all found no effect on testosterone or androgen markers. The 'natural test booster' positioning is contradicted by controlled human trials.
- The one real benefit is sexual function — improved erectile scores in men and desire scores in women — but this effect is independent of testosterone (in the male RCT, testosterone actually fell while erections improved). The best male trial (Kamenov 2017) was manufacturer-involved.
- Saponin and protodioscin content varies wildly between products and regions, so 'standardized to X% saponins' is a weak guarantee of active dose.
- Adulteration is a documented problem: banned anabolic steroids have been found in athlete-marketed Tribulus products. This likely explains some 'it worked / I tested positive' reports and is a real doping and liver-injury risk. The Australian Institute of Sport classifies Tribulus as high-risk-of-contamination.
Frequently asked
Does Tribulus terrestris raise testosterone?
No — not in controlled human trials. A randomized trial in young men found no change in testosterone, androstenedione, or LH (Neychev 2005); a trial in rugby players found no change in the testosterone/epitestosterone ratio (Rogerson 2007); and an anti-doping study confirmed no effect on endogenous testosterone metabolism (Saudan 2008). The testosterone-booster claim comes from animal studies that don't translate to humans.Then why do some people say it works?
Two reasons. First, Tribulus does seem to modestly improve sexual function (erections in men, desire in women) — but that's a libido effect, not a testosterone effect, and people often conflate the two. Second, some athlete-marketed Tribulus products have been found adulterated with undeclared anabolic steroids, which would produce real 'androgenic' effects that have nothing to do with the herb.Does Tribulus help with erectile dysfunction or libido?
Modestly, based on limited evidence. A 12-week RCT in 180 men (Kamenov 2017) improved erectile-function scores versus placebo — while testosterone actually dropped slightly, so the effect is androgen-independent. A small trial in women improved sexual-desire scores. Both rely on subjective questionnaires, and the strongest male trial was funded with manufacturer involvement, so treat it as promising rather than proven.Is Tribulus safe?
The herb itself is generally well tolerated at typical doses, with mild GI upset the most common complaint. The bigger risks are sourcing-related: there's a case report of liver, kidney, and neurological toxicity from concentrated use, and — more importantly — surveys have found banned anabolic steroids in athlete-marketed Tribulus products. NIH LiverTox notes some 'Tribulus liver injury' cases were more likely caused by undisclosed steroid use. Buy only third-party-tested products, and athletes should be especially wary.What dose should I take?
There's no validated therapeutic dose because saponin content varies so much between products. The positive sexual-function trials used a standardized extract (Tribestan® 750 mg/day, standardized to furostanol saponins). If you're considering it for libido, use a defined, standardized, third-party-tested extract — and don't expect any testosterone or strength benefit.
References
- 01Neychev & Mitev, 2005 — Tribulus does not influence androgen production in young men (J Ethnopharmacol)
- 02Rogerson et al., 2007 — Tribulus, strength and body composition in rugby players (J Strength Cond Res)
- 03Kamenov et al., 2017 — Tribestan® for male sexual dysfunction RCT (Maturitas)
- 04Pokrywka et al., 2014 — Tribulus supplements used by athletes, review (J Hum Kinet)
- 05NIH LiverTox — Tribulus (NCBI Bookshelf)
- 06Examine.com — Tribulus terrestris
Last reviewed2026-05-24