Objective  To evaluate the efficacy and tolerance of tamoxifen (TAM) in the treatment of idiopathic oligozoospermia.

Methods  Clinical data of 123 patients diagnosed with idiopathic oligozoospermia in Department of Sterility and Sexual Medicine of the Third Affiliated Hospital of Sun Yat-sen University from February 1, 2021 to August 30, 2023 were retrospectively analyzed. All patients with a sperm density of ＜ 15×10⁶/mL were treated with 10 mg TAM twice a day for 4 months or longer. The changes of semen (n = 123) and serum hormones (n = 71) were assessed in patients with idiopathic oligozoospermia treated with TAM. The efficacy of TAM for oligozoospermia was evaluated. Sperm parameters and hormones among different groups were compared by Friedman test, and two-group comparison was performed by Bonferroni’s correction.

Results  After treating 3 and 4 months, the sperm density (Z = 7.428, 5.101; both P ＜ 0.05) and the total number of sperm (Z = 6.280, 3.379; both P ＜ 0.05) in patients with idiopathic oligozoospermia were increased compared with those before treatment. Compared with treating for 3 months, the total number of sperm was decreased after treating for 4 months (Z = −2.901, P = 0.011). Compared with before treatment, the total sperm motility tended to increase after 3- and 4-month TAM treatment, but the differences were not statistically significant (Z = 4.503, P = 0.105). Compared with before treatment, the serum testosterone levels (Z = 5.203, 4.238; both P ＜ 0.05) and the estradiol levels (Z = 3.944, 3.734; both P ＜ 0.05) were increased after 3- and 4- months TAM treatment. Compared with before treatment, the improvement rate of sperm density was 62.6% (77/123) after 3 months TAM treatment and 49.6% (61/123) after 4 months TAM treatment.

Conclusions  TAM can enhance the sperm density and total number of sperm in patients with idiopathic oligozoospermia. However, special attention should be paid to the efficacy and tolerance of TAM treatment.