In addition to assessing your detailed history about a prior allergic reaction to penicillin, allergists administer skin tests to determine if you are allergic to the medication. These tests, which are conducted in our office, typically take about two to three hours, including the time needed after testing to watch for reactions.
Penicillin is a common cause of drug allergy. Just because you show allergic symptoms after taking penicillin doesn’t mean that you will react to related drugs, such as amoxicillin, but it’s more likely. Also, just because you had a reaction to penicillin or any other drug at one time doesn’t mean you will have the same reaction in the future.
When safely and properly administered, skin tests involve pricking the skin, injecting a weakened form of the drug and observing your reaction. People who reacting negatively to the injection are seen as low risk for an immediate acute reaction penicillin. The allergist might then give your a full-strength oral dose to confirm the absence of a penicillin allergy.
Those with positive allergy skin tests should avoid penicillin and be treated with a different antibiotic. In some cases if penicillin is recommended, your can undergo penicillin desensitization to enable you to receive the medication in a controlled manner under the care of an allergist.
If you have severe reactions to penicillin, you should seek emergency care, which may include an epinephrine injection and treatment to maintain blood pressure and normal breathing. If you have milder reactions and suspect that an allergy to penicillin is the cause, you may be treated with antihistamines or, in some cases, oral or injected corticosteroids, depending on the reaction.