Tribulus Terrestris for Female Sexual Dysfunction: A Systematic Review.

The short version

This systematic review of five randomized controlled trials (279 women) examined whether Tribulus terrestris, a creeping herb used as a natural sexual stimulant, improves female sexual dysfunction (FSD) and what safety data exist. All participants had hypoactive sexual desire disorder (HSDD, persistently low sexual desire that causes distress) or loss of libido. Tribulus extracts contain protodioscin, a steroidal saponin (plant compound with hormone-like structure) proposed to increase luteinizing hormone, the pituitary hormone that stimulates androgen production. The review cites estimates that 30 to 50% of women experience FSD during their lifetime, and notes that the effects of Tribulus had not been established. Reviewers searched six databases and trial registries up to February 2019 for trials comparing Tribulus with placebo or another treatment. The trials took place in Brazil (four) and Iran (one) and enrolled 172 postmenopausal women (43 to 65) and 107 premenopausal women (18 to 44). Four trials gave 250 mg by mouth three times daily for 90 to 120 days; one gave a syrup twice daily for 30 days. Sexual function was measured with the Female Sexual Function Index (FSFI, scored 2 to 36) and the Sexual Quotient Female Version (SQ-F, scored 0 to 100); higher scores mean better function. Differences between trials prevented pooling results. One trial in 67 premenopausal women found a higher FSFI total score after one month on Tribulus (mean difference 4.39 points; 95% CI 2.90 to 5.88, a statistically reliable gain), driven by arousal, lubrication, orgasm and satisfaction rather than desire or pain. Two other FSFI trials at three months found no significant difference (p = 0.19 and p = 0.44). In 60 postmenopausal women, SQ-F scores rose by 16.40 points (95% CI 7.67 to 25.13) at three months. Testosterone rose in premenopausal women (mean difference 6.60; 95% CI 0.27 to 12.93) but not in postmenopausal women (2.50; 95% CI -1.79 to 6.79, a range that includes no effect). Only one trial reported adverse events: none serious, and one case of abdominal cramps. No trial measured quality of life. The authors rate the certainty of the evidence as very low, meaning future studies are likely to change the estimates. Trials were small, selection methods were unclear, and two trials lost 20% and 37.5% of participants. The authors state that current evidence does not support routine clinical use and call for more well-designed randomized trials in pre- and postmenopausal women. They note the main limitation was that only one of the contacted trial authors supplied additional data, and that this is the first systematic review of Tribulus for FSD.

Key findings

• Five randomized trials with 279 women who had low sexual desire found that Tribulus terrestris, a plant used as a natural sexual stimulant, was compared with placebo for 1 to 4 months.
• Sexual function scores were higher with Tribulus in single trials: one month of treatment raised the Female Sexual Function Index score by 4.39 points in 67 premenopausal women, and three months raised the Sexual Quotient Female score by 16.40 points in 60 postmenopausal women.
• Two other trials measuring the Female Sexual Function Index found no significant difference from placebo after three months (p = 0.19 and p = 0.44).
• Testosterone rose in premenopausal women (by 6.60) but not in postmenopausal women, and only one trial reported side effects, with no serious events and one case of abdominal cramps.
• The authors rate the certainty of the evidence as very low, meaning the true effect could be very different, and state that current evidence does not support routine clinical use of Tribulus for female sexual dysfunction.

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