SUPPLEMENTS
The supplements that actually have evidence for men’s sexual health
Twelve popular ingredients, what each one is, what the studies measured and who took part, plus the safety points worth knowing before you choose.
Several supplement ingredients have been studied for men's sexual health, with the most research on L-arginine, tongkat ali and antioxidants such as CoQ10. In a pooled analysis of 10 trials in men with mild to moderate erection problems, those taking L-arginine reported better erectile function scores than those on placebo1, and a meta-analysis of tongkat ali trials found higher total testosterone2. This guide sets out what each ingredient is, what the studies measured and who took part.
L-arginine has the largest body of trials for erectile function, in men with mild to moderate erection problems.
Tongkat ali, ashwagandha and fenugreek have been studied for testosterone, with positive findings in trials of different sizes and designs.
Zinc and selenium have authorised UK and EU health claims: zinc contributes to normal fertility and reproduction, and selenium contributes to normal spermatogenesis.
CoQ10, selenium and lycopene have mainly been studied in men attending fertility clinics, often as part of antioxidant combinations.
Who was studied matters: many results come from men with a specific diagnosis or a low baseline level, and research is ongoing for other groups.
Check with a pharmacist or GP before starting a supplement if you take other medicines, and stick to the amounts on the label.
Which supplements have been studied for men's sexual health?
The ingredients with the most published research are L-arginine and L-citrulline for erectile function, tongkat ali, ashwagandha, fenugreek and vitamin D for testosterone, maca for libido, and zinc, selenium, lycopene and CoQ10 for sperm quality. The tables below summarise what each one is and who took part in the studies.
Supplement research asks three different questions: does an ingredient change a lab measurement, does it change something people notice, and in whom? A study in men with a diagnosed condition or a low starting level may not tell you much about men without one. So for every ingredient here we describe what was measured and who took part, and we link to our glossary for the background.
Ingredient
What it is
What studies have looked at
Who was studied
Amino acid used to make nitric oxide
Erectile function scores
Men with mild to moderate erectile dysfunction
Amino acid the body converts to arginine
Erection hardness
Men with mild erectile dysfunction
Root extract of Eurycoma longifolia
Total testosterone
Healthy men and men with low testosterone
Ayurvedic herb, Withania somnifera
Testosterone, DHEA-S, vitality
Overweight men aged 40 to 70
Seed extract of Trigonella foenum-graecum
Total and free testosterone
Adult men in placebo-controlled trials
Andean root, Lepidium meyenii
Sexual desire and function
Healthy men, cyclists, men with erectile dysfunction
Ingredient
What it is
What studies have looked at
Who was studied
What have studies found on supplements for erections?
L-arginine has the most trials: in a meta-analysis of 10 randomised trials involving 540 men with mild to moderate erectile dysfunction, erectile function scores improved more with arginine than with placebo or no treatment1. L-citrulline and ginseng have smaller positive trials34.
L-arginine
The body uses L-arginine to make nitric oxide, which helps blood vessels relax, including those involved in erections. The 2019 meta-analysis pooled trials in which men took between 1,500 and 5,000 mg a day1. Men taking arginine had 3.37 times the odds of improvement compared with placebo or no treatment, with gains in overall satisfaction, intercourse satisfaction, orgasmic function and erectile function scores. Sexual desire scores did not change. Side effects were reported by 8.3% of men taking arginine and 2.3% on placebo, and none were severe. Treatment length and dose varied between trials, which the authors noted as a limitation.
L-citrulline
L-citrulline is converted into arginine in the body. In a small single-blind study, 24 men with mild erectile dysfunction took a placebo for one month and then 1.5 g of L-citrulline a day for another month3. Erection hardness improved to the top score in 12 of the 24 men (50%) while taking citrulline, compared with 2 (8.3%) on placebo, and no side effects were reported. The authors called for further research.
Ginseng and tribulus
A 2018 meta-analysis of 24 trials in 2,080 men with erectile dysfunction found that ginseng improved erectile function scores compared with placebo across five trials4. For tribulus, results have varied between the two trials included. No significant differences in adverse events between the herbal products and placebo were found in the placebo-controlled trials, and the authors called for larger studies.
When to see a doctor
Erection problems that last more than a few weeks are worth discussing with a GP, who can check for underlying causes such as blood pressure, blood sugar or medication side effects and talk you through tested treatments.
Tell your doctor or pharmacist about any supplement you take, especially if you use blood pressure medicines, nitrates or prescription erection tablets. Seek help promptly for sudden changes, pain, a curve that is getting worse or blood in your semen.
Which supplements have been studied for testosterone?
Tongkat ali, ashwagandha, fenugreek and vitamin D have all been tested in randomised trials. Tongkat ali raised total testosterone in a meta-analysis of five trials2, ashwagandha raised it in an eight-week trial of 57 men5, and fenugreek showed a small favourable effect across six trials6.
Tongkat ali. A 2022 systematic review included nine studies, five of which were pooled in a meta-analysis2. Total testosterone rose significantly in men taking Eurycoma longifolia, in both healthy volunteers and men with low testosterone, and the finding held in the low-testosterone subgroup. The authors described it as a promising area and said more research is needed.
Ashwagandha. In a 16-week crossover trial, overweight men aged 40 to 70 with mild fatigue took an ashwagandha extract or placebo for eight weeks each5. Ashwagandha was associated with an 18% greater increase in DHEA-S and a 14.7% greater increase in salivary testosterone compared with placebo. Fatigue, vigour and sexual well-being improved over time in both groups, and the authors called for larger studies.
Fenugreek. A 2026 meta-analysis of randomised, placebo-controlled trials found a small favourable effect on total testosterone across six trials; results for free testosterone varied between studies6. The authors rated the certainty of the evidence as very low, and research is ongoing.
Vitamin D. Vitamin D contributes to the maintenance of normal muscle function, an authorised health claim in the UK and EU. For testosterone, a 12-week trial gave 98 healthy men with normal testosterone and lower vitamin D levels either 20,000 IU a week or placebo; total testosterone was similar in the two groups at the end7. Research in men with low testosterone is ongoing.
Zinc also carries an authorised claim here: zinc contributes to the maintenance of normal testosterone levels in the blood. If you are concerned about your own levels, a blood test is the place to start; our guide to testosterone after 40 explains what's involved.
Which supplements have been studied for libido?
Maca has the most direct research on sexual desire. A systematic review found four randomised trials, including one in healthy adult men that reported a positive effect on sexual desire and one in men with erectile dysfunction that reported improved scores8.
Maca is an Andean plant from the brassica (mustard) family, and its root is the part used. Of the four trials in the review, two reported positive effects on sexual desire or sexual dysfunction, one in healthy menopausal women and one in healthy men; one in healthy cyclists found no difference; and one in men with erectile dysfunction reported improvements8. The reviewers noted that the trials were few and small, and that more rigorous studies are warranted. The 2018 herbal meta-analysis also described early positive results for maca in erectile dysfunction4.
Desire is influenced by many things, including sleep, stress, relationships, mood, medicines and hormones. Our sexual health check can help you think through which of these might apply to you.
What does research show on supplements for sperm and fertility?
Zinc contributes to normal fertility and reproduction, and selenium contributes to normal spermatogenesis; both are authorised UK and EU health claims. In a Cochrane review of antioxidant trials in men attending fertility clinics, pregnancy and live birth rates were higher with antioxidants, though the reviewers rated the evidence low to very low certainty9.
Antioxidants, selenium and lycopene
Oxidative stress can damage sperm, which is the idea behind antioxidant supplements. The 2022 Cochrane review pooled 90 studies of 10,303 men with fertility problems who were attending clinics, testing 20 different antioxidants alone or in combination9. Antioxidants were associated with higher live birth rates (odds ratio 1.43) and clinical pregnancy rates (odds ratio 1.89) than placebo or no treatment. The reviewers rated the evidence low to very low certainty, noted that results varied with study quality, and called for larger trials.
“Further large well-designed randomised placebo-controlled trials studying infertile men and reporting on pregnancy and live births are still required to clarify the exact role of antioxidants.”
One of those larger trials, MOXI, gave 174 men with male-factor infertility a daily combination of vitamins C and E, selenium, L-carnitine, zinc, folic acid and lycopene, or placebo, for three to six months; there were no significant differences in sperm shape, motility or DNA fragmentation, and live birth rates did not differ between the groups10.
Zinc and folate
The largest trial in this area enrolled 2,370 couples planning fertility treatment in the US. The men took 5 mg of folic acid with 30 mg of zinc daily, or placebo, for six months; most semen quality measures and live birth rates were similar in the two groups11. We look at zinc in more detail in zinc and semen volume.
CoQ10
Coenzyme Q10 helps cells produce energy and acts as an antioxidant. A 2021 systematic review found that all included studies reported a beneficial effect of CoQ10 on semen parameters in men with fertility problems12. The authors noted that randomised trials were a minority and that the best dose is not yet known, and described it as a promising area for further research.
Are supplements for sexual health safe?
Most ingredients here were well tolerated in trials, but side effects do occur. Mild stomach upsets were more common with antioxidants than placebo in the Cochrane review9, and side effects were more frequent with L-arginine (8.3%) than placebo (2.3%), though none were severe1.
In the zinc and folic acid trial, abdominal discomfort, nausea and vomiting were somewhat more common in the supplement group than with placebo11. Beyond trial side effects, a few practical points apply to any supplement:
Stick to the label. Long-term high intakes of some nutrients, including zinc and vitamin D, can cause harm, and several products can add up to more than you realise.
Check interactions. Ask a pharmacist before combining supplements with blood pressure medicines, nitrates, erection tablets, blood thinners or diabetes medicines.
Take extra care with health conditions. If you have heart, liver, kidney or thyroid problems, or a hormone-sensitive condition, check with your GP first.
Give it time. Fertility trials measured semen after three to six months1011, and several of the erection and testosterone trials described here ran for one to three months357.
Quick self-check: should you talk to a pharmacist first?
I take blood pressure medicines, nitrates or erection tablets.
I take blood thinners or diabetes medicines.
I'm already taking more than one supplement with overlapping ingredients.
I'm not sure how much of each ingredient my product contains.
I have a symptom I haven't yet discussed with a doctor.
I have a heart, liver, kidney or thyroid condition.
Tap the statements that apply to you.
If several of these apply, take your supplement labels to a pharmacist or GP before starting. They can check interactions and amounts. For habits that also affect fertility and sexual health, see our guide to lifestyle factors.
Myth or fact?
Myth: Natural products can't have side effects.
Myth: Taking more gives faster results.
Fact: Trials tested specific amounts over weeks to months, and high intakes of some nutrients can cause harm, so stick to the amounts on the label.
Myth: You should notice a difference within days.
Fact: Fertility trials measured semen after three to six months11, and erection and testosterone trials ran for weeks to months, so judge any change over a similar period.
Myth: A supplement can stand in for seeing a doctor.
Fact: Persistent erection problems, low desire or fertility worries can have medical causes that are worth checking. Supplements are best seen as one part of looking after your health.
Frequently asked questions
Which supplement has the most research for erections?
L-arginine, with a meta-analysis of 10 randomised trials in men with mild to moderate erectile dysfunction1. L-citrulline and ginseng have smaller positive trials.
Is zinc good for male fertility?
Zinc contributes to normal fertility and reproduction and to the maintenance of normal testosterone levels in the blood; both are authorised UK and EU health claims. Zinc is found in foods such as meat, shellfish, dairy and bread; if you think you might be low, ask your GP.
Does ashwagandha raise testosterone?
In an eight-week trial of overweight men aged 40 to 70, ashwagandha was associated with a 14.7% greater increase in salivary testosterone than placebo5. The authors called for larger studies.
What does tongkat ali do?
Tongkat ali has mainly been studied for testosterone. A meta-analysis of five randomised trials found higher total testosterone in men taking it, including men with low testosterone2.
How long do supplement studies usually last?
Are supplements regulated like medicines?
No. In the UK and EU, food supplements are regulated as foods rather than medicines, and only authorised health claims can appear on their labels. That is why you will see claims for vitamins and minerals such as zinc and selenium, but not for most herbal ingredients.
[1] Rhim HC, et al. The potential role of arginine supplements on erectile dysfunction: a systemic review and meta-analysis. J Sex Med. 2019;16(2):223-34. PubMed
[2] Leisegang K, et al. Eurycoma longifolia (Jack) improves serum total testosterone in men: a systematic review and meta-analysis of clinical trials. Medicina (Kaunas). 2022;58(8):1047. PubMed
[3] Cormio L, et al. Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction. Urology. 2011;77(1):119-22. PubMed
[4] Borrelli F, et al. Herbal dietary supplements for erectile dysfunction: a systematic review and meta-analysis. Drugs. 2018;78(6):643-73. PubMed
[5] Lopresti AL, Drummond PD, Smith SJ. A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha (Withania somnifera) in aging, overweight males. Am J Mens Health. 2019;13(2):1557988319835985. PubMed
[6] Yang P, et al. Effects of oral fenugreek-derived preparations on testosterone-related outcomes in adult men: a systematic review and meta-analysis of randomized placebo-controlled trials. Front Nutr. 2026;13:1903508. PubMed
[7] Lerchbaum E, et al. Vitamin D and testosterone in healthy men: a randomized controlled trial. J Clin Endocrinol Metab. 2017;102(11):4292-302. PubMed
[8] Shin BC, et al. Maca (L. meyenii) for improving sexual function: a systematic review. BMC Complement Altern Med. 2010;10:44. PubMed
[9] de Ligny W, et al. Antioxidants for male subfertility. Cochrane Database Syst Rev. 2022;5(5):CD007411. PubMed
[10] Steiner AZ, et al. The effect of antioxidants on male factor infertility: the Males, Antioxidants, and Infertility (MOXI) randomized clinical trial. Fertil Steril. 2020;113(3):552-60. PubMed
[11] Schisterman EF, et al. Effect of folic acid and zinc supplementation in men on semen quality and live birth among couples undergoing infertility treatment: a randomized clinical trial. JAMA. 2020;323(1):35-48. PubMed
[12] Salvio G, et al. Coenzyme Q10 and male infertility: a systematic review. Antioxidants (Basel). 2021;10(6):874. PubMed
Eric Stephens
Eric Stephens writes and edits every guide on Load Boosting. He reads and summarises peer-reviewed research and major medical-society guidance on men’s health, and links to every source.