Before you start taking Penicillin V, tell your doctor:, About all the medications you take, including prescription and nonprescription medications., About your allergies., About your current health problems and past medical history., If you are pregnant or breastfeeding., Penicillin V should be used with caution in patients with kidney problems., Taking Penicillin V for a long period of time can lead to superinfection, hemolytic anemia, serum sickness, or abnormal blood counts., Penicillin V should be used with caution in neonates., Penicillin V should be used with caution in patients with seizure disorders. About all the medications you take, including prescription and nonprescription medications., About your allergies., About your current health problems and past medical history., If you are pregnant or breastfeeding.