Tribulus: Dangers, Side Effects, and Contraindications, According to Studies

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Tribulus terrestris

An extract of Tribulus terrestris fruit standardized to 90% saponins, in vegetable capsules. Three capsules per day, with a large glass of water and preferably with meals, provide 471 mg of extract, or 424 mg of saponins.

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The Tribulus terrestris is a creeping plant from warm regions, whose spiny fruit is rich in steroidal saponins, such as protodioscin. It is sold for libido, erectile function, and athletic performance. In a 2024 survey conducted in Italian gyms, 7.8% of the 510 respondents were taking it at the time of the study, and those seeking performance primarily consumed it significantly more often (adjusted odds ratio of approximately 18.5).

To assess danger, the best source remains the randomized controlled trial against placebo, and those on tribulus are consistent. A recent meta-analysis combined 8 studies on erectile dysfunction: erectile function score improved more than with placebo, total testosterone did not differ between groups, and neither did the incidence of adverse effects.

A 2025 systematic review devoted to men goes in the same direction. Out of 10 studies, 483 participants aged 16 to 70, with 400 mg to 12 g per day for 4 weeks to 3 months, none reported any side effects or abnormalities in lipid or liver function tests, but half were of low quality. In women, a review of 5 randomized trials, 279 participants treated for 1 to 3 months, found no serious adverse effects, with certainty of evidence judged as very low.

In 67 non-menopausal women treated for 4 weeks with a leaf extract syrup, adverse effects were systematically sought at 1, 2, and 4 weeks: only one participant reported a grade 1 abdominal cramp, the mildest level. In 60 menopausal women treated for 90 days, the frequency of adverse effects did not differ from placebo.

A trial conducted in 45 menopausal women, with 750 mg per day for 120 days, is the most transparent on dropouts: 3 participants from each group, tribulus as well as placebo, were excluded due to side effects. This identical figure suggests effects not specific to the plant.

In men, a trial conducted in 70 aging men with partial androgen deficiency, treated for 3 months, noted small biological variations in the tribulus group: the liver enzyme ASAT increased on average from 26.5 to 27.8, and total PSA, a marker monitored for the prostate, from 1.4 to 1.7, without worsening of urinary symptoms. These variations are small, but should be reported to one's doctor if PSA monitoring is being done.

Our Tribulus terrestris provides 471 mg of fruit extract per day in 3 capsules. The trials used 400 to 1,500 mg of extract per day; the largest, in 180 men, 1,500 mg of an aerial parts extract. The comparison ends there: the extracts tested came from different plant parts and regions, with saponin standardizations ranging from 40 to 60% in the male studies, while ours is standardized at 90%. For efficacy, our analysis tribulus and libido details the results trial by trial.

On the kidney side, published cases are real, few in number but sometimes severe. A review of cases of renal toxicity related to plants and supplements, published from 1966 to 2016, classifies tribulus among approximately 7 plants associated with kidney damage.

The 2010 Iranian case. A 28-year-old man drank a tribulus preparation for 2 days to prevent kidney stones. He experienced seizures, very elevated transaminases and creatinine, which improved upon discontinuation. It was a "water" prepared from the plant, taken at high dose according to a 2014 review.

The case of 2015. A young, healthy man taking tribulus as a sports supplement developed severe jaundice followed by acute kidney failure; biopsy showed necrosis of kidney tubules with bile casts, an injury linked to excess bilirubin.

The 2024 authors summarize an earlier case, very likely the 2015 one: a 30-year-old man taking tribulus tablets as part of a bodybuilding program, with bilirubin at 39 mg/dL and creatinine at 3.1 mg/dL, returning to 4.4 and 1.2 mg/dL six weeks after discontinuation.

These cases are rare : a few publications for a plant consumed worldwide. The causality is not established : a 2020 review emphasizes that the supplements in question were not analyzed and no clinical trial reported this type of effect, and a medication was associated in the 2024 case. It is not ruled out either: improvement upon discontinuation in the 2010 and 2015 cases argues for a link; in the 2024 case, the injury persisted and only regressed after plasma exchanges. The liver and kidney lesions also resemble those observed in animals. Jaundice or dark urine with tribulus requires immediate discontinuation and evaluation.

Priapism. In 2015, Italian urologists described a 36-year-old man who experienced a prolonged erection of 72 hours after taking a tribulus-based supplement. Surgical shunting was necessary, with sequelae to sexual function. The supplement was not analyzed, and the 2020 review judges that no conclusion can be drawn from it. Painful erection lasting more than 4 hours is a medical emergency, regardless of the cause.

Gynecomastia. In 2004, a British team reported gynecomastia, that is, breast gland development, in a young bodybuilding practitioner taking a plant-based tablet containing tribulus as an alternative to steroids. Unique case, product not analyzed.

Rhabdomyolysis with a statin. In 2024, a 71-year-old man treated for 6 years with atorvastatin 40 mg daily started a tribulus capsule at 500 mg daily. Two weeks later, he arrived at the emergency department with muscle pain: his CPK, the enzyme released by damaged muscle, peaked at 11,972 IU/L on the fourth day, with elevated transaminases (ASAT at 542 IU/L) but without kidney involvement. The authors hypothesize an interaction through CYP3A4 enzyme inhibition, which degrades atorvastatin: a hypothesis, not a demonstration.

For livestock farmers, tribulus is a well-known toxic plant. A systematic review of 166 reports of poisoning by photosensitization in livestock, published in 20 countries, places Tribulus terrestris among the three most frequent causes of hepatic-origin photosensitization worldwide, along with two forage grasses. In this form, the most frequent (68.5% of diagnoses), it is liver damage that makes the skin abnormally sensitive to sunlight.

There is a second, neurological form: sheep that graze on tribulus for long periods can develop asymmetric motor impairment of the hind legs, described in 28 sheep in Australia. A 2020 review attributes it to the plant's beta-carbolines; the mechanism remains debated.

Should this be transposed to humans? Not directly: an intoxicated sheep consumes the whole plant, up to 80% of its diet, for days, when a supplement provides only a few hundred milligrams of extract. These observations nonetheless identify the organs to monitor, liver and kidneys: we therefore classify this risk as rare but real.

Tribulus is often sold as a "testosterone booster," which also raises concerns about hormonal effects. Studies confirm neither one nor the other. In 21 men aged 20 to 36, 10 or 20 mg of extract per kilogram per day for 4 weeks did not modify neither testosterone, nor androstenedione, nor LH hormone, all remaining within normal range. In 30 men aged 40 and older suffering from erectile dysfunction, 800 mg daily for 30 days performed no better than placebo, neither on erection nor on testosterone. In 30 infertile men, 750 mg daily for 3 months did not modify hormones or sperm count.

The reviews confirm this. A 2014 systematic review concludes that tribulus does not increase testosterone in men, with increases only appearing when it is part of a mixture of ingredients. A 2024 review of 27 "testosterone boosters" does not rank it among the rare effective exceptions. The most recent 2025 review counts 8 studies out of 10 without change in androgenic profile; the two exceptions, of poor quality, concerned men with low testosterone, with a modest increase of 60 to 70 ng/dL.

In men, the absence of measurable hormonal effect makes adverse effects specific to androgens unlikely. If your goal is testosterone, our guides for naturally increasing testosterone and on testosterone boosters detail what really works.

Two questions arise: does the plant modify testing markers, and can a supplement contain a banned substance? On the first, studies are reassuring. In 22 elite rugby players, 450 mg of extract per day for 5 weeks did not modify the urinary testosterone to epitestosterone ratio, the hormonal marker monitored during testing. In a study conducted by a Swiss anti-doping laboratory, two athletes who tested positive claimed to have taken tribulus; two volunteers then took 500 mg three times daily for 2 days, with no significant variation in steroid profile or isotopic analysis. In 2025, a pilot study conducted in 8 men and 7 women taking an extract daily for 2 months found no significant modification of urinary steroid profile.

The risk for a tested athlete therefore does not come from the plant but from contamination. On the performance side, in rugby players, strength gains were identical with placebo. Our guide on doping and banned substances details precautions to take, and our analysis of pre-workouts lists ingredients with measured effects.

Tribulus is not a single substance. Its composition varies depending on harvest region, season, plant part, and extraction method: a 2020 review reported for example that protodioscin, the major saponin in European plants, was absent from samples harvested in Vietnam and India. Therefore, a trial result cannot be transposed from one extract to another.

On this panel: no steroids, but 6 products out of 27 with ingredients absent from the label. The authors note that green tea extracts have been associated with hepatitis cases. In our view, this complicates interpretation of hepatic cases attributed to tribulus when the product has not been analyzed.

Diabetes and antidiabetic medications. In 98 women with type 2 diabetes, 1,000 mg daily of a hydroalcoholic extract for 3 months lowered blood glucose more than placebo, as well as total cholesterol and LDL. With antidiabetic medication, the effect could be additive: no cases have been published, the risk is theoretical but is based on a measured effect in humans. Our guide on High blood sugar presents the other options studied.

Blood Pressure and Antihypertensive Medications. In adults with borderline blood pressure, 6 g per day of dried fruit powder for 2 months reduced systolic pressure by 7.7 mmHg and diastolic pressure by 5.5 mmHg, compared to 1.9 and 0.2 mmHg under placebo. This was fruit powder, not an extract. With antihypertensive medication, the additive effect is theoretical but plausible.

Statins and Other Medications. The case of rhabdomyolysis under atorvastatin remains isolated. A 2020 review adds two theoretical leads: saponins could increase the absorption of other compounds, and tribulus alkaloids inhibit monoamine oxidase, hence caution with MAOI antidepressants. For lithium, we found neither study nor case: the precaution is based solely on the traditional use of tribulus as a diuretic.

Pregnancy and Breastfeeding. No human data exists: trials excluded pregnant women. In pregnant ewes fed dried tribulus late in gestation, the pregnancy outcome was not modified, but fetal respiratory movements were less frequent, a possible sign of an effect on fetal brain development according to the authors. Due to lack of data, it is best avoided during pregnancy and breastfeeding.

Hormone-Dependent Cancers. In the laboratory, on yeast, an aqueous extract of the whole plant showed estrogenic activity starting at 27 µg/mL, whereas methanol and chloroform extracts were anti-estrogenic. This in vitro signal, combined with increased free testosterone measured in women, justifies avoiding tribulus in case of personal or family history of hormone-dependent cancer. The risk remains theoretical.

These precautions are those of our Tribulus terrestris, not recommended for pregnant and breastfeeding women, women with personal or family history of breast cancer, children and adolescents, and in case of antihypertensive or antidiabetic treatment. For blood pressure, our guide to naturally regulate your blood pressure presents the studied approaches.

Tribulus appears in many formulas for libido, vitality, or muscle building. A systematic review catalogued the ingredients of the best-selling men's supplements online in the United States: tribulus was one of the most frequent, and no complete product had undergone a published trial. The concrete risk: taking a tribulus supplement and a formula that already contains it, and adding up the saponins. This combination has not been studied, the only study at 12 g per day cited by the 2025 review is of poor quality, and published cases set no threshold. The practical rule is therefore to take only one source of tribulus at a time and to read the composition of each formula.

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Male Libido

Four plants combined in one formula : three capsules per day with meals provide 300 mg of muira puama extract, 285 mg of ginger root, 285 mg of tribulus at 90% saponins, or approximately 256 mg of saponins, and 150 mg of ginseng extract providing 30 mg of ginsenosides.

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Our formula Male Libido itself contains 285 mg of tribulus. Combining it with our Tribulus terrestris would add up the tribulus saponins from both products, approximately 680 mg per day: this should not be done. Choose one or the other. Male Libido is not recommended for adolescents and in case of antihypertensive or antidiabetic treatment, and it contains ginseng, which has its own precautions. Our comparison maca, tribulus and ginseng summarizes the trials conducted with each of these plants.

"Established" designates a solid finding, "rare" isolated cases in humans, "theoretical" a risk deduced from a mechanism or measured effect with no published cases, "misconception" an assertion that studies contradict.

Doses and durations come from trials; the rest falls under practical caution.

If the goal is libido or erectile function, other options exist. A meta-analysis of 14 trials conducted in 1,227 men with erectile dysfunction found an effect of saffron and ginseng, and judged evidence still insufficient for other plants such as maca. A 2022 review places sleep, physical activity and weight loss in case of obesity before any supplement, and cites zinc, as well as vitamin D in case of deficiency, among the rare promising nutrients in men with low testosterone. Our Zinc provides 14.16 mg of zinc and 2 mg of vitamin B6 per 2 capsules, and our Plant-based Vitamin D3 1,000 IU per drop; a blood test can determine if you're deficient. Our article on male fertility details this information. Finally, persistent erectile dysfunction warrants a consultation: effective treatments exist.

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