I recently had an allergic reaction to penicillin and was treated at the local emergency room. I am a pharmacy technician, and now I have been removed from my job until I can produce evidence of what, if anything, will happen to me when counting penicillin or its derivatives. That may involve breathing in pill dust or touching the medication. I can't find any information on this. Can you help me?

Dawn

There are several types of allergy to penicillin. The most serious reaction is an immediate hypersensitivity. With this allergic reaction, within 30-60 minutes of exposure to the drug -- sometimes sooner -- the patient develops hives. When the reaction is severe, the person also can develop such serious problems as swelling in the throat and hypotension (abnormally low blood pressure), which can lead to death if prompt treatment is not given. Fortunately, these severe reactions are quite uncommon. Far more often, the allergic person develops a morbilliform (measles-like) rash, which occurs several days after exposure to the drug and is rarely life-threatening. In addition, many people who claim to have an allergy to penicillin actually do not. Frequently, a rash occurs as part of an illness, not as a response to penicillin treatment, and the drug is an innocent bystander.
I would like to know whether you had a true allergic reaction to penicillin, and if so, the type of reaction you experienced. If it was an immediate reaction, then you could be at some risk after exposure to penicillin and related antibiotics. People who have an allergy to penicillin and related drugs also can have allergic reactions to other classes of antibiotics, such as the cephalosporins and carbapenems. However, I doubt that you are at significant risk simply because you have been exposed to penicillin multiple times in the past and have not had any problems (at least none that you mentioned).

There are allergy tests that can be performed to determine whether you have immediate hypersensitivity to penicillin. IgE antibodies, proteins made by the body's immune system, play a key role in such allergic reactions. Skin testing will determine whether you have IgE antibodies directed against penicillin -- or more precisely, IgEs directed against the breakdown products of penicillin, which trigger this type of reaction.

Any allergist can perform this testing, and I urge you to see one. Unfortunately, in the United States, it has been difficult to obtain some of the best testing agents for this purpose, but the ones that are available are adequate for most cases. The allergist simply injects a tiny amount of the agent into the skin and looks for a hive. There can be other factors that can interfere with the results of such tests, so the allergist uses a positive control (a substance that is known to cause an allergic response) and negative control (a substance that does not trigger an allergic response) to help with this determination.