Meta-analysis of the efficacy and safety of L-carnitine and N-acetylcysteine monotherapy for male idiopathic infertility.

BACKGROUND

Oral antioxidants especially L-carnitine (LC) and N-Acetylcysteine (NAC) are commonly used as the drug treatment method for idiopathic male infertility (IMI).

METHODS

Randomized controlled trials (RCTs) of LC and NAC monotherapy for IMI were searched systematically by using MEDLINE, EMBASE and the Cochrane Controlled Trials Register. The reference lists of retrieved studies were also perused. We analyzed the sperm concentration, normal morphology, sperm motility, and ejaculation volume.

RESULTS

Seven Randomized controlled trials were included. Four trials compared the efficacy of LC with placebo, and three trials compared the efficacy of NAC with placebo. In the efficacy analysis, LC increased sperm concentration ( < 0.001), normal morphology ( = 0.03), and sperm motility ( = 0.02); NAC improved the first three indicators while also increasing ejaculation volume ( = 0.002). In hormone level analysis, LC increased serum testosterone levels ( < 0.001), but the changes in other hormone levels were not statistically significant.

CONCLUSIONS

Both LC and NAC can improve sperm motility, sperm concentration, and normal morphology, and increase serum testosterone concentration, but have no significant effect on other serum hormones.

THE PROSPERO REGISTRATION

CRD42024552120.

©2025 The Author(s). Published by MRE Press.