Several kinds of conditions are specifically related to penicillin allergies. These include:

• Group B streptococci (GBS). Some physicians recommend that some pregnant women take penicillin to avoid passing on GBS (bacterial infection that can harm newborns) to their babies. Though penicillin is the first choice for treatment, pregnant women who are allergic to penicillin can treat this condition with other antibiotics as well.
  
  
• Cephalosporin allergy. Part of the basic chemical structure is the same for both the penicillin and cephalosporin (antibiotics that include cefaclor and cephalexin) family. Because of the chemical similarities, a person with a penicillin allergy may have a cross-reaction when taking cephalosporins. This is a rare type of condition, however.
  
  
• Penicillium allergy. Inhaled mold is one of the most common types of allergens associated with hay fever (allergic rhinitis). One type of mold, penicillium, is used to make the drug penicillin. Some individuals are allergic to penicillium when it is inhaled. However, there is no relationship between a respiratory allergy to penicillium and an allergy to the drug penicillin. Individuals who are allergic only to penicillin will not experience any type of allergic reaction when they inhale this type of mold.

Because of similarities in symptoms, the cause of a penicillin allergy may go unrecognized. A penicillin allergy shares symptoms with many other common allergies, including:

• Allergic rhinitis. Inflammation of the mucous membrane that lines the nose, due to an allergic reaction to pollen, dust or other airborne substances. Symptoms include runny nose and itchy eyes.

  

• Allergic conjunctivitis. Inflammation of the tissue lining the inside of the eyelid caused by an allergic reaction. Symptoms include itchy eyes.
  

  

• Allergic sinusitis. Inflammation of the lining of the sinus cavities in the face caused by an allergic reaction. Symptoms can include runny nose and nasal congestion.
  

  

• Food allergy. An allergic reaction to a specific type of food (e.g., peanuts, seafood).  Symptoms include nausea, itching and hives.

Penicillin is generally not taken if the patient has a history of bleeding problems, kidney disease, liver disease, infectious mononucleosis or stomach or intestinal diseases. Patients with these conditions should always discuss the use of penicillin with their physician before taking the drug.