Acyclovir also should be given if neonates are ill-appearing, have mucocutaneous vesicles, have a maternal history of genital herpes simplex virus (HSV) infection, or have seizures, hypothermia, leukopenia, thrombocytopenia, or elevated alanine aminotransferase (ALT); acyclovir is stopped if CSF HSV PCR testing and mucocutaneous vesicle HSV culture (if done) results are negative.