Penicillin is part of a family of drugs known as beta–lactam antibiotics. An allergy to one form of penicillin means that every drug in the beta–lactam family can be dangerous. Other types of penicillin are used to combat different types of infections in various parts of the body. The several types of penicillin an allergic individual must be careful to avoid include:

• Amoxicillin. The most commonly used type of beta–lactam, this drug is often used in the treatment of strep throat and ear infections.
  
  
• Ampicillin. Able to penetrate and prevent the growth of various forms of bacteria. It is often used to treat infections of the middle ear, sinuses, bladder and kidney.
  
  
• Dicloxacillin. Used to treat bacterial infections of the lungs and skin.
  
  
• Nafcillin. Often used to treat infections caused by staphylococcus bacteria (staph infections).
  
  
• Penicillin V. Used to treat ear infections and tonsil infections. It can also prevent recurrence of rheumatic fever and skin infections from streptococcus bacteria.
  
  
• Penicillin G. Used to treat bacterial infections of the ear, nose, and throat, skin and soft tissues and respiratory tract.
  
  
• Azlocillin. Widely used, though mainly for the treatment of pseudomonas infections that lead to urinary tract infections, sepsis and pneumonia.
  
  
• Mezlocillin. Commonly used to treat infections of the lungs, urinary tract and skin.
  
  
• Oxacillin. Commonly used to treat penicillin–resistant staph infections.
  
  
• Piperacillin. Used to treat moderate and severe infections.