Hello, I would be happy to help you with your question.
To quote from a reputable source:
was found to cause....temporary depression in spermatogenesis
and reduction in sperm viability and sperm count were also reported in mice."
He needs to contact a Urologist
who should check a semen analysis
and counsel him appropriately regarding its use and potential for decrease in fertility and affect on sperm.
I hope that this helps and good luck!