Fenugreek and male libido: what clinical studies show

Fenugreek ( Trigonella foenum-graecum , fenugreek) is often mentioned in the context of men's health, libido, and testosterone. But the clinical evidence does not boil down to a simple formula of "fenugreek increases testosterone - therefore libido increases." In some randomized trials, sexual function has been improved even without a significant increase in testosterone, and a recent meta-analysis shows only a small average effect on total testosterone and an inconsistent result for free testosterone.

This makes fenugreek interesting precisely as an example of a herbal ingredient where the subjective effect may depend on several mechanisms simultaneously: androgenic status, vascular response, general well-being, and probably the composition of the specific extract.

What major clinical studies show

Fenugreek and Libido: Why Testosterone Doesn't Explain Everything

Testosterone is essential for male sexual desire, especially when levels are truly low. However, libido is not a direct reflection of a single lab test. It is influenced by sleep, stress, psychoemotional state, energy balance, the nervous system, other hormones, and the quality of sexual response.

That is why the study by Steels et al. 2011 is indicative. Men who received 600 mg of a standardized fenugreek preparation for six weeks improved individual components of sexual function, although no clear increase in serum testosterone was observed.

In a 2016 study by Rao et al., the picture was different: 600 mg of a standardized extract for 12 weeks was accompanied by both improved sexual function and changes in testosterone. In particular, the authors reported a higher frequency of morning erections and sexual activity.

Thus, clinical data suggest at least two scenarios: sexual function may improve with changes in androgen levels or may change without appreciable increases in testosterone. This does not prove a separate “libido-mechanism” for fenugreek, but it does show that assessing its effects based on total testosterone alone is not sufficient.

How much does fenugreek really increase testosterone?

The most comprehensive current assessment is provided by a systematic review and meta-analysis by Yang et al. 2026. It included 13 randomized placebo-controlled trials in adult men.

For total testosterone, six studies with 385 participants yielded a small positive effect: the standardized difference in mean SMD was 0.25 with a 95% confidence interval of 0.02–0.48.

For free testosterone, five studies with 334 participants yielded an SMD of 0.08 with a 95% confidence interval of −0.48 to 0.63. That is, the meta-analysis did not confirm a consistent overall effect on free testosterone.

The authors rated the quality of evidence for both hormonal outcomes as very low. Reasons include small sample sizes, different types of extracts, different methods of hormone determination, risk of bias, and a significant proportion of studies related to specific commercial formulations.

Therefore, it is more correct to speak not about a guaranteed "testosterone boost", but about a small positive signal for total testosterone, which needs to be confirmed by better quality studies.

What is known about sexual function?

In a 2026 meta-analysis, Yang et al. separately analyzed male health-related outcomes. The composite score of the DISF—a questionnaire of sexual function—was better in the fenugreek groups, with a mean difference of 16.97 points with a 95% confidence interval of 6.06–27.88.

At the same time, the authors specifically warn against drawing too strong conclusions. The number of studies on sexual function is small, the drugs differed in composition, and positive changes in questionnaires do not prove that the effect was caused by testosterone.

This is an important distinction. Libido, frequency of sexual activity, morning erections, and laboratory testosterone levels are all related, but not interchangeable.

Fenugreek contains steroidal saponins, furostanol glycosides, sapogenins, trigonelline, 4-hydroxyisoleucine, polyphenols, and other compounds. The composition of different extracts varies significantly.

The popular explanation of the action through “stimulation of testosterone production” is still too simplistic. Human studies have not established a single mechanism by which fenugreek saponins consistently enhance testosterone synthesis in the testicles.

Similarly, diosgenin should not be treated as a ready-made precursor of testosterone for the human body. Diosgenin has a steroid structure and is used as a raw material for the chemical synthesis of steroid compounds in industry, but this does not mean that after ingestion the human body converts it into testosterone.

The most conservative interpretation of the current data is that individual standardized fenugreek preparations may affect the androgen profile in some men, but the magnitude and mechanism of this effect are uncertain.

Possible mechanism: nitric oxide and blood flow

Libido and erection are not the same thing. Libido is sexual desire, while erection is largely dependent on a neurovascular response.

One of the key physiological pathways for erection is the nitric oxide system: NO activates guanylate cyclase, increases cGMP levels, and promotes relaxation of the smooth muscles of the corpora cavernosa. This allows for increased blood flow to the tissues.

For fenugreek, there is preclinical evidence that makes this mechanism biologically plausible. Qiu et al. (2024) showed in models of endothelial dysfunction that fenugreek extract reduced arginase-1 pathway activity and increased NO production.

However, these were cell and animal models, not human erection studies. Therefore, the correct conclusion is limited: effects on NO and endothelial function are a possible mechanism, but it has not yet been proven that this explains the improvements in sexual function in clinical trials of fenugreek.

Why subjective effects can be more noticeable than changes in analyses

If a particular extract affects multiple systems at once, even small changes can add up. Theoretically, androgenic status, vascular reactivity, energy status, and overall well-being could all contribute to a noticeable result.

This may explain why a person notices a more pronounced change in sexual desire or sexual activity than would be expected from a small change in total testosterone.

However, a subjectively noticeable effect alone does not allow us to determine the mechanism. To understand whether a hormonal change has occurred in a particular person, laboratory indicators are needed, not just well-being.

What does "fenugreek 50% saponins" mean?

Standardization of “50% saponins” means that the manufacturer declares a certain total proportion of compounds that the analysis method attributes to the saponin fraction. But this figure does not describe the full chemical profile of the extract.

Two extracts with the same label "50% saponins" may differ in the ratio of individual furostanol glycosides, protodioscin, diosgenin derivatives and other components. In addition, different laboratory methods for determining "total saponins" do not always give directly comparable results.

This is one reason why the results of Testofen, Fenu-FG, Furosap, Trigozim and other standardized preparations cannot be automatically transferred to any fenugreek extract with the same total percentage of saponins.

What can be said from the totality of the evidence?

• In several randomized trials, standardized fenugreek preparations improved certain measures of male sexual function.
• In some studies, this effect was accompanied by changes in testosterone, and in others, it was not.
• A 2026 meta-analysis shows a small positive effect on total testosterone, but does not confirm a consistent increase in free testosterone.
• The potential effects on NO and endothelial function have experimental support but have not yet been proven as a mechanism for improving sexual function in humans.
• The effect of a specific standardized extract cannot be automatically transferred to all fenugreek preparations.

Safety and precautions

No serious adverse events that investigators attributed to fenugreek have been reported in short-term randomized trials. However, in a 2026 systematic review, the authors noted that the follow-ups were relatively short, the samples were small, and the collection of adverse event data was inconsistent.

Fenugreek may cause gastrointestinal discomfort and individual reactions. Since the plant is also being studied in the context of its effect on glycemic control, people taking diabetes medications should consider the possibility of interactions. In case of chronic diseases or ongoing medication, it is advisable to coordinate the use of supplements with a doctor.

Persistent decreased libido or erectile dysfunction should not be automatically attributed to “low testosterone.” Causes may be hormonal, vascular, metabolic, psychological, or drug-related, so persistent symptoms require separate evaluation.

Fenugreek has more interesting clinical data on male sexual function than would be expected from its simple image as an “herbal testosterone booster.” In some randomized trials, standardized extracts have improved libido, sexual activity, or frequency of morning erections, although these changes have not always been accompanied by significant increases in testosterone.

According to the current meta-analysis, the effect on total testosterone is on average small, and a consistent effect on free testosterone has not been confirmed. Therefore, it is more logical to consider the potential effect of fenugreek as a complex, rather than a simple stimulation of testosterone synthesis.

The most important limitation of the evidence base is that different standardized extracts are not chemically identical. Therefore, the percentage of total saponins is useful for characterizing the raw material, but by itself does not guarantee the reproducibility of the results of a specific clinical preparation.

Frequently asked questions

Can fenugreek increase male libido?
Several randomized trials have shown that standardized fenugreek preparations have improved certain measures of sexual function. However, the number of such studies is small, so the effect cannot be guaranteed.

Does improved libido mean increased testosterone?
No. In one clinical study, sexual function improved without a clear increase in serum testosterone, so these measures do not always change synchronously.

How much does fenugreek increase testosterone?
A recent meta-analysis shows a small, medium positive effect on total testosterone. No consistent effect was found for free testosterone, and the overall quality of the evidence was rated as very low by the authors.

Can fenugreek affect erections through nitric oxide?
This mechanism is biologically possible: in preclinical models, fenugreek extract has been shown to affect the arginase-1 pathway and NO production. However, there is no direct evidence that this mechanism improves erections in humans.

What does fenugreek extract 50% saponins mean?
This is a standardization by the total content of the saponin fraction. It does not show the exact ratio of individual saponins, so different extracts with the same "50%" may have different compositions.

Can Testofen results be transferred to any fenugreek extract?
No. Testofen and other studied preparations have their own standardization and chemical profile, so the results of a particular extract should not be automatically transferred to other forms.

Is fenugreek a treatment for erectile dysfunction?
No. The available evidence relates to the potential support of individual measures of sexual function, but fenugreek is not a substitute for the diagnosis and treatment of erectile dysfunction.

Sources

• Yang P., Niu Z., Guo J., Huang T., Chang D., Huang X. (2026). Effects of oral fenugreek-derived preparations on testosterone-related outcomes in adult men: a systematic review and meta-analysis of randomized placebo-controlled trials. Frontiers in Nutrition . https://doi.org/10.3389/fnut.2026.1903508
• Steels E., Rao A., Vitetta L. (2011). Physiological aspects of male libido enhanced by standardized Trigonella foenum-graecum extract and mineral formulation. Phytotherapy Research . https://pubmed.ncbi.nlm.nih.gov/21312304/
• Rao A, Steels E, Inder WJ, Abraham S, Vitetta L (2016). Testofen, a specialized Trigonella foenum-graecum seed extract reduces age-related symptoms of androgen decrease, increases testosterone levels and improves sexual function in healthy aging males in a double-blind randomized clinical study. The Aging Male . https://pubmed.ncbi.nlm.nih.gov/26791805/
• Thakurdesai P. et al. (2024). Effect of a plant extract of fenugreek (Trigonella foenum-graecum) on testosterone in blood plasma and saliva in a double blind randomized controlled intervention study. https://pubmed.ncbi.nlm.nih.gov/39288153/
• Qiu D., Hu J., Zhang S., Cai W., Miao J., Li P., Jiang W. (2024). Fenugreek extract improves diabetes-induced endothelial dysfunction via the arginase 1 pathway. Food & Function . https://pubmed.ncbi.nlm.nih.gov/38450419/
• Burnett AL (1995). Role of nitric oxide in the physiology of erection. Biology of Reproduction . https://pubmed.ncbi.nlm.nih.gov/7756443/

Dietary supplement. Not a medicine. Consult a doctor before use.