5-FU injection and topical even in small doses cause both acute central nervous system (CNS) damage and progressively worsening delayed degeneration of the CNS in mice. This latter effect is caused by 5-FU-induced damage to the oligodendrocytes that produce the insulating myelin sheaths.
Home > Sexually transmitted infections > Syphilis > After treatment for syphilis. It is strongly advised that you do not have any sexual intercourse; including vaginal; anal or oral sex until you and your partner(s) have both finished the treatment and any follow-up treatment.
1 A pregnant woman with syphilis must have penicillin, even if she is allergic to it. She must tell her doctor of this allergy to allow for desensitization procedures.  After treatment with penicillin, a Jarisch-Herxheimer reaction may occur 2-12 hours after treatment starts.