Does magnesium help fertility and testosterone?

On the trials that exist, no. A 2025 meta-analysis of 4 randomized trials in 248 women with polycystic ovary syndrome found 250 mg of magnesium a day for 8 to 20 weeks did not change testosterone, a difference of 0.16 ng/dL lower with an interval from 0.50 lower to 0.18 higher. In the only randomized trial in men, 20 men with unexplained infertility, magnesium improved neither sperm nor pregnancy rates. We found no trial that measured ovulation, pregnancy or live birth with magnesium on its own.

Myth. The claim that magnesium raises testosterone rests mainly on a 2011 study in young men that was neither randomized nor placebo controlled. It gave 10 mg of magnesium per kg of body weight a day for 4 weeks, which for an adult of ordinary weight is above the 350 mg upper limit for supplements, and it does not report how many men took part. In the randomized evidence the effect has not appeared.

What the trials found

Women with polycystic ovary syndrome

All four trials in the 2025 meta-analysis came from Iran and carried some concerns about bias. Beyond testosterone, magnesium did not change DHEA, the free androgen index or SHBG, and it did not clearly change weight, fasting glucose or insulin resistance. The authors concluded that magnesium does not appear to influence hormonal and cardiometabolic factors in PCOS. One of the four was an 8-week trial in 60 women on 250 mg of magnesium oxide, where the difference in testosterone against placebo did not reach significance.

A 2022 systematic review of 9 randomized trials in 363 women with PCOS reached the same answer for magnesium alone on glucose, lipids, inflammation and oxidative stress. Combinations did better. In a 12-week trial of 60 women, 250 mg of magnesium with 400 mg of vitamin E a day lowered hirsutism scores against placebo, and nobody can say how much of that was the magnesium. One trial of magnesium with zinc, calcium and vitamin D in PCOS has been retracted.

Unsettled. A 2026 meta-analysis of 11 randomized trials in 618 women with PCOS found that mineral supplements lowered insulin resistance, a standardized difference of 0.75 on HOMA-IR. Magnesium was pooled with chromium, zinc and selenium, and the analysis reported nothing on hormones or fertility. It cannot be read as a result for magnesium.

Men

The one randomized trial gave 20 men with unexplained infertility 3000 mg of magnesium orotate a day or placebo for 90 days. Sperm concentration, movement and shape did not change significantly, and pregnancy rates in their partners did not rise. It was a pilot with 10 men in each group. A 2024 systematic review of 52 studies of supplements sold as testosterone boosters, 5 of them on zinc or magnesium, found that most fail to raise total testosterone against placebo. Zinc and magnesium were not among those it judged effective.

Links in observational data

Among 299 infertile men, those in the highest third of blood magnesium had a sperm concentration of 20.9 million per ml against 8.6 million in the lowest third, with no difference in FSH, LH or inhibin B. Those men were not given magnesium, so this is a link and not an effect.

Other comparisons are weaker still. A 2025 meta-analysis of 38 studies in 5070 men found no difference in semen magnesium between infertile and fertile men. A 2021 meta-analysis of 8 studies in 2026 women found blood magnesium 0.09 mmol/L lower in women with PCOS, an interval from 0.02 to 0.17 lower, with very high heterogeneity between the studies.

Who should be careful

Not for everyone. The upper limit for magnesium from supplements is 350 mg a day for adults, and 65 to 350 mg for children and teenagers depending on age. Food is not counted. High doses can cause diarrhea, nausea and cramping, and the risk of toxicity rises when the kidneys work poorly. The 250 mg used in the PCOS trials is under the limit. The dose by body weight in the 2011 study is above it. The 3000 mg in the trial in men is the weight of magnesium orotate tablets, not of magnesium alone.

Quinolone and tetracycline antibiotics should be taken at least 2 hours before or 4 to 6 hours after a magnesium supplement. We found no evidence on magnesium supplements for fertility in women trying to conceive or in pregnancy, which is a separate question on this site.

What expert bodies say

We found no expert body that recommends magnesium for fertility or testosterone. The 2023 international guideline on PCOS does not make a magnesium recommendation that we could find. The European and American urology guidance on supplements for male infertility that we checked does not name magnesium, and its text was not available to quote, so it is not used as a source here.

How we searched

What would change this answer

• A randomized trial of magnesium within the upper limit, in men or in women with PCOS who are short of magnesium, that reports ovulation or pregnancy. We found none registered.
• A placebo-controlled trial of the testosterone claim in men, with a dose under 350 mg a day.
• Trials of magnesium on its own, kept apart from vitamin E, zinc and other minerals.

What magnesium does, how much you need and who runs short is on the magnesium guide.

Sources

1. ev-mgfe-01 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 6 articles from 4 RCTs, 248 patients
   Our meta-analysis indicated that magnesium supplementation does not significantly affect DHEA (MD: −5.13 µg/dL; 95% CI: −43.26, 33.00, I2 = 80.20%), testosterone (MD: −0.16 ng/dL; 95% CI: −0.50, 0.18, I2 = 76.64%), FAI (MD: −0.11; 95% CI: −1.30, 1.08, I2 = 0.00%), and SHBG (MD: 0.81 nmol/L; 95% CI: −8.32, 9.93, I2 = 0.00%) levels in patients with PCOS (Figure 7).
   
   Who: women with polycystic ovary syndrome aged 25 to 32, BMI 26 to 30, magnesium 250 mg/day for 8 to 20 weeks vs control
   Effect: testosterone MD -0.16 ng/dL (95% CI -0.50 to 0.18); DHEA MD -5.13 ug/dL (-43.26 to 33.00); FAI MD -0.11 (-1.30 to 1.08); SHBG MD 0.81 nmol/L (-8.32 to 9.93)
   Certainty: All RCTs are from Iran, "some concerns" on RoB; fertility (ovulation, pregnancy) was not measured.
   Medicina (Kaunas), 2025 · checked 2026-10-07 · we read the fulltext
2. ev-mgfe-02 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 6 studies (4 RCTs)
   Conclusions: Magnesium supplementation does not appear to influence the cardiometabolic and hormonal factors in PCOS patients.
   
   Who: women with polycystic ovary syndrome in RCTs of magnesium vs control
   Effect: HOMA-IR MD -0.00 (95% CI -1.34 to 1.33); fasting glucose MD -3.94 mg/dL (-10.91 to 3.03); body weight MD -1.4 lb (-4 to 1.2; metric: -0.62 kg, -1.80 to 0.55)
   Certainty: The first MA specifically of magnesium in PCOS; small volume.
   Medicina (Kaunas), 2025 · checked 2026-10-07 · we read the abstract
3. ev-mgfe-03 · Meta-analysis or systematic review · systematic review of RCTs (no pooled meta-analysis) · n = 9 RCTs, 363 patients
   Magnesium intake alone did not lead to a significant improvement in the markers of OS, blood glucose, or serum lipids in PCOS.
   
   Who: women with PCOS in RCTs of magnesium alone or with vitamin E, zinc, calcium, vitamin D or melatonin
   Effect: magnesium alone: no significant change; with vitamin E or zinc-calcium-vitamin D: lower hs-CRP, insulin, HOMA-IR, TG, TC
   Certainty: Combinations do not allow attributing the effect to magnesium; one RCT of the Mg-Zn-Ca-D combination (28668998) was retracted.
   Front Endocrinol (Lausanne), 2022 · checked 2026-10-07 · we read the abstract
4. ev-mgfe-04 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs · n = 11 RCTs, 618 women
   Mineral supplementation was associated with significant reductions in fasting blood glucose (SMD = − 0.34, p < 0.001), fasting insulin (SMD = − 0.72, p < 0.001), and HOMA-IR (SMD = − 0.75, p < 0.001).
   
   Who: women with PCOS, mineral supplement vs placebo
   Effect: HOMA-IR SMD -0.75; fasting insulin SMD -0.72; fasting glucose SMD -0.34 (all p < 0.001)
   Certainty: Magnesium is pooled with other minerals; does not report on fertility and hormones. Metabolism is an indirect pathway to ovulation.
   BMC Endocr Disord, 2026 · checked 2026-10-07 · we read the abstract
5. ev-mgfe-05 · Meta-analysis or systematic review · systematic review of placebo-controlled studies · n = 52 studies of 27 proposed boosters (5 zinc/magnesium)
   Our findings indicate that most fail to increase total testosterone.
   
   Who: male athletes, men with late-onset hypogonadism, infertile men and healthy men
   Effect: most boosters no increase in total testosterone vs placebo; zinc/magnesium not among those judged effective
   Certainty: The full text is not available for the Zn/Mg figures; the conclusion is for the group as a whole.
   Int J Impot Res, 2024 · checked 2026-10-07 · we read the abstract
6. ev-mgfe-06 · Randomized controlled trial(s) · randomized, placebo-controlled pilot trial · n = 20 men (10 per group)
   In conclusion, magnesium-orotate treatment at a dose of 3000 mg/day leads neither to a significant improvement of sperm variables nor does it increase the pregnancy rates of female partners of treated males as compared to those of controls.
   
   Who: males with idiopathic infertility, 3000 mg magnesium orotate daily for 90 days vs placebo
   Effect: no significant change in sperm concentration, motility or morphology; 1 pregnancy in the magnesium group
   Certainty: Very small pilot RCT; the only RCT of magnesium on sperm.
   Magnes Res, 2003 · checked 2026-10-07 · we read the abstract
7. ev-mgfe-07 · Randomized controlled trial(s) · parallel randomized, double-blind, placebo-controlled trial · n = 60 women
   Magnesium supplementation had no significant effects on FSH, 17OH-progesteron, sex hormone-binding globulin (SHBG), and free androgen index (FAI) levels.
   
   Who: women with PCOS aged 20 to 45, 250 mg magnesium oxide vs placebo for 8 weeks
   Effect: testosterone between-group difference P = 0.08; no effect on FSH, SHBG, FAI; BMI -0.31 vs +0.07 kg/m2
   Certainty: Included in the 2025 meta-analysis (ev-mgfe-01). LH rose in the magnesium group.
   Biol Trace Elem Res, 2020 · checked 2026-10-07 · we read the abstract
8. ev-mgfe-08 · Randomized controlled trial(s) · randomized, double-blind, placebo-controlled trial · n = 60 women
   Magnesium and vitamin E co-supplementation resulted in a significant reduction in hirsutism (β - 0.37; 95% CI, - 0.70, - 0.05; P = 0.02) and serum high-sensitivity C-reactive protein (hs-CRP) (β - 0.67 mg/L; 95% CI, - 1.20, - 0.14; P = 0.01), and a significant increase in plasma nitric oxide (NO) (β 3.40 μmol/L; 95% CI, 1.46, 5.35; P = 0.001) and total antioxidant capacity (TAC) levels (β 66.32 mmol/L; 95% CI, 43.80, 88.84; P < 0.001).
   
   Who: women with PCOS aged 18 to 40, 250 mg/day magnesium plus 400 mg/day vitamin E vs placebo for 12 weeks
   Effect: hirsutism beta -0.37 (95% CI -0.70 to -0.05); hs-CRP beta -0.67 mg/L (-1.20 to -0.14)
   Certainty: Combination with vitamin E; the contribution of magnesium alone is unknown.
   Biol Trace Elem Res, 2019 · checked 2026-10-07 · we read the abstract
9. ev-mgfe-09 · Observational data · controlled clinical trial, not randomized · n = 3 study groups (size not given in abstract)
   Our results show that supplementation with magnesium increases free and total testosterone values in sedentary and in athletes.
   
   Who: tae kwon do athletes and sedentary young men, magnesium sulfate 10 mg/kg body weight daily for 4 weeks
   Effect: free and total testosterone increased with supplementation; larger rise with exercise
   Certainty: No randomization and no placebo; 10 mg/kg for an adult over 77 lb (35 kg) exceeds the UL of 350 mg. The main source of the myth "magnesium raises testosterone".
   Biol Trace Elem Res, 2011 · checked 2026-10-07 · we read the abstract
10. ev-mgfe-10 · Observational data · secondary cross-sectional analysis of an RCT cohort · n = 299 men
    RESULTS: Sperm concentration and total sperm count were higher in men in the highest serum magnesium tertile compared with men in the lowest serum magnesium tertile (20.9 million/ml versus 8.6 million/ml, P = 0.007; 72 million versus 37 million, P = 0.009, respectively).
    
    Who: infertile men from a vitamin D trial, stratified by serum magnesium tertile
    Effect: sperm concentration 20.9 vs 8.6 million/ml (P = 0.007); total sperm count 72 vs 37 million (P = 0.009); FSH, LH, inhibin B no difference
    Certainty: Association, not a supplement effect; magnesium was not given in the RCTs.
    Reprod Biomed Online, 2026 · checked 2026-10-07 · we read the abstract
11. ev-mgfe-11 · Observational data · systematic review and meta-analysis of observational studies · n = 8 studies (10 arms), 2026 women
    Pooled effect sizes, expressed as WMD and 95% CI, revealed decreased serum Mg concentrations in women with PCOS compared with controls (- 0.09 (- 0.17, - 0.02) mmol/L; P = 0.01).
    
    Who: women with vs without polycystic ovary syndrome
    Effect: serum Mg WMD -0.09 mmol/L (95% CI -0.17 to -0.02); I2 98%
    Certainty: Difference small, I2 98%; lower Mg mostly in overweight.
    Biol Trace Elem Res, 2021 · checked 2026-10-07 · we read the abstract
12. ev-mgfe-12 · Observational data · systematic review and meta-analysis of case-control studies · n = 38 studies, 5070 participants
    No significant differences in male infertility patient cases and healthy controls were found for Zn, Fe, Mn, Se, Ca, Mg, and Pb in semen.
    
    Who: infertile men vs healthy controls, semen element levels
    Effect: semen Mg no significant difference; Cu and Cd higher in infertility
    Certainty: Observational data; an argument against magnesium deficiency as a cause of male infertility.
    Toxicol Lett, 2025 · checked 2026-10-07 · we read the abstract
13. ev-mgfe-13 · Position of an expert body · government fact sheet · n = —
    The Tolerable Upper Intake Level for supplemental magnesium is 350 mg for adults, and it ranges from 65 to 350 mg for children and adolescents, depending on age.
    
    Who: adults; children and adolescents 65 to 350 mg
    Effect: UL 350 mg/day supplemental magnesium (food not counted)
    Certainty: Doses in the PCOS RCT (250 mg) are below the UL; 10 mg/kg (ev-mgfe-09) is above. 3000 mg of orotate (ev-mgfe-06) is the mass of the salt, not of elemental magnesium; it is not compared with the UL directly.
    NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals · checked 2026-10-07 · we read the section
14. ev-mgfe-14 · Position of an expert body · government fact sheet · n = —
    The risk of magnesium toxicity increases with impaired renal function or kidney failure because the ability to remove excess magnesium is reduced or lost [1,29].
    
    Who: people taking high-dose magnesium supplements; people with impaired renal function
    Effect: diarrhea, nausea, abdominal cramping; toxicity risk higher with kidney failure
    NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals · checked 2026-10-07 · we read the section
15. ev-mgfe-15 · Position of an expert body · government fact sheet · n = —
    These antibiotics should be taken at least 2 hours before or 4 to 6 hours after a magnesium-containing supplement [57,62].
    
    Who: people taking magnesium supplements with quinolone or tetracycline antibiotics
    Effect: separate doses to avoid insoluble complexes
    NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals · checked 2026-10-07 · we read the section