It is generally safe to drink alcohol in moderation while taking penicillin, as alcohol does not reduce the effectiveness of penicillin or cause serious interactions. However, drinking alcohol may slow recovery from infection and increase side effects such as dizziness, stomach upset, and drowsiness that both penicillin and alcohol can cause. Therefore, it is usually recommended to avoid alcohol until the antibiotic course is finished and the illness is getting better. If in doubt, consult the prescribing doctor or pharmacist for personalized advice based on health and medication details.