Yes, it is very common to experience a lack of semen during ejaculation while taking these medications. Specifically, Silodal (silodosin), which is prescribed to help relax your urinary tract, frequently causes a harmless and temporary condition where semen flows backward into the bladder instead of coming out. The other medications, Altacef (cefuroxime), Pantocid (pantoprazole), and Flavospas (flavoxate), do not typically cause this. This side effect is completely safe, does not affect your virility, and will fully resolve within a few days after you finish your course of Silodal.