Problem: Despite the therapeutic and nutritional benefits of Justicia carnea, some of its phytochemicals are antinutritional and harmful if consumed. Reduction in testicular weight, sperm count/motility, testosterone levels, and abnormal testicular histology have  been reported following administration of ethanol extracts of J. carnea (EJC). Nutraceuticals can utilize these negative effects to benefit mankind as these supposedly harmful effects can be harnessed in the current search for "ideal" male contraceptive. This study aimed at assessing the possible adverse effects of oral administration of boiled aqueous extracts of J.carnea leaves (AJC) and the EJC on serum testosterone and seminalysis (sperm count, motility and morphology) of male albino rats as possible candidate male contraceptive. Approach: Forty-two male Wistar albino rats (12-14 weeks old) in seven groups were used. The control was fed grower feed and water only. Test groups were in addition given 200, 400 and 600mg/kg body weight (BW) of either EJC or AJC for 21d(21 days). The first batch (drawn from each group) were sacrificed a day later while the second batch were continued on feed and water only for further 52d after discontinuation before sacrificing them. Serum testosterone was determined by ELISA and seminalysis done by mounting semen smear preparations on microscope and viewing.  SPSS version 25 was used for analysis of results while (P< 0.05) was regarded significant. Findings: After 21d of treatment, no significant change in serum testosterone was noted in comparison with the control for both extracts’ treated groups. However, 52d after discontinuation, the serum testosterone of rats administered 400mg/kg BW of both extracts were significantly higher than the control and other groups. There was no significant change in total sperm count of all the treatment groups when compared with the control after 21d of administration. But 52d after discontinuation, the total sperm count for the group administered 400mg/kgBW EJC was significantly lower than the other groups and the control. There was no significant change in sperm motility in all the groups administered both extracts after 21d compared to the control. By 52d after discontinuation, there was significant reduction in sperm motility in rats administered 400 and 600mg/kg BW AJC. There was no significant change in sperm motility in rats administered 200mg/kg BWEJC, 400mg/kg BW and 600mg/kg BWAJC. There was a significant increase in the abnormal morphology of the group that received 400mg/kg BW AJC compared to the other groups. This was noted to have reversed by 52dafter discontinuation. The group that received 400mg/kg BW EJC had no significant change in the abnormal morphology at 21dafter administration, but a significant increase in abnormal morphology was noted 52d after discontinuation.

Conclusion: Both extracts of J.carnea when administered for 21dadversely impact some male reproductive indices in albino rats, such as testosterone level and seminalysis at the doses used. This can be explored in the development of male contraceptive.