The penicillins as a group are the most frequently and widely used of the antimicrobial agents because they are effective, low in toxicity, and relatively inexpensive. Effectiveness is due to the bactericidal action, the excellent distribution throughout the body spaces, and the wide spectrum of activity. Knowledge of the variation in spectrum of activity of the various types of penicillins is needed for effective use of the proper drug against individual infections. Allergenicity is the most frequent and serious problem associated with the use of penicillins. However, individual penicillin drugs do have other toxic side effects. The older penicillins are so inexpensive that the cost of their use need hardly be considered, whereas the newer penicillins are expensive and should be used only when they are clearly more effective for treatment than are drugs such as penicillin G.
青霉素类药物作为一个整体，是最常使用且使用范围最广的抗菌药物，因为它们疗效显著、毒性低且相对便宜。其有效性源于杀菌作用、在全身各腔隙中的良好分布以及广泛的活性谱。为了针对个体感染有效使用合适的药物，需要了解各类青霉素活性谱的差异。过敏反应是使用青霉素类药物最常见且最严重的问题。然而，个别青霉素药物确实还有其他毒副作用。较老的青霉素非常便宜，以至于几乎无需考虑其使用成本，而较新的青霉素则价格昂贵，仅应在它们明显比青霉素G等药物更有效地用于治疗时才使用。
