People who have had allergic reactions to penicillin in the past, or whose parents may have allergies to penicillin, should get tested for any potential reaction before taking penicillin medications. Penicillin, like all medications, can cause a range of adverse reactions. Some of these reactions may be caused by an allergy to the penicillin, while other reactions may be undesirable side effects that result from a person's sensitivity to the medicine. Nonallergic side effects may include an upset stomach, discomfort and vomiting. Alternatively, symptoms that indicate an allergic reaction to penicillin include a rash, hives, itchy skin, wheezing, angioedema and anaphylactic shock. Because an allergic reaction can be life-threatening, it's vital to differentiate between who is allergic to this antibiotic and who is simply sensitive.
Skin testing is the most reliable method for detecting penicillin allergies. To conduct this test, an allergist will inject a diluted amount of penicillin into the skin on your forearm or back. This area will be observed for signs of a reaction. People with a true allergic reaction will develop a red, raised bumpy rash in the area that is injected. This rash will last for about half an hour and may cause itching. Skin testing, which takes about an hour to complete, must be done by a trained allergist in a clinic or hospital setting to ensure the patient's safety. If you test positive to a penicillin allergy, you doctor will recommend that you avoid this antibiotic.
If you test negative to a skin test of penicillin, you will then be given a single oral dose of full-strength penicillin to make sure that you did not receive a false-negative result. If you have no reaction to both the skin test and oral test, then you can rest assured that you have no allergy to penicillin. On the other hand, people who develop extensive blistering and peeling of the skin, which resembles a sunburn-like reaction, or those who develop a rash that is composed of tiny bumps that resemble a bulls-eye should avoid penicillin for the rest of their lives. These types of reactions suggest an extremely sensitive allergy to penicillin, which may be life-threatening; a second exposure to the drug may result in a severe progressive reaction and even death.