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What You Need to Know About Medication Allergies

by The GoodRx Pharmacist on April 8, 2015 at 1:02 pm

When you drop off your medications at a pharmacy you may notice that the technician, intern, or pharmacist who greets you and takes your prescriptions may also ask you for an updated list of your allergies.

I have seen some patients annoyed by this life-saving question, while others seem to blow it off. Some of the remarks I have heard include, “It’s on file, I told you last time,” to “You don’t need to know this information.”

You may not know that disclosing your allergies to the pharmacy may just save your life from a life threatening allergic reaction. In fact, for your safety, it’s important to tell not only your pharmacy about your allergies, but every doctor that cares for you as well. It is also a good idea to keep a list of your current medications and allergies on your person at all times in case of an emergency.

Something else that may not be clear to a lot of people is the difference between allergic reactions and adverse reactions. Believe it or not, these two terms do not mean the same thing.

An allergic reaction occurs when your body is exposed to a medication and reacts negatively by releasing a chemical known as histamine. Histamine release can then lead to itching, hives, swelling of the lips, eyes, mouth, or even throat. A severe allergic reaction, if not treated properly, can be fatal. You can have an allergic reaction to a variety of medications, though antibiotics are a common example.

Adverse reactions are also known as side effects. Adverse reactions to medications include, but aren’t limited to, headache, upset stomach, nausea, vomiting, diarrhea, and constipation. An upset stomach, for example, is an adverse reaction, NOT an allergic reaction.

It is important to know the difference between an allergic reaction and adverse reaction or side effect when updating your doctor or pharmacist on your current allergies.

The following are examples of some common allergies and medications that might trigger them. Please know that this list is NOT all-inclusive, and you should discuss any concerns about medication allergies with your doctor or your pharmacist.

Sulfa Allergy

Penicillin allergy

Peanut allergy

Egg allergy

  • Vaccinations, including the flu and yellow fever vaccines

Gelatin allergy

  • Vaccinations, including the flu, yellow fever, MMRV (MMR with chickenpox), shingles, and varicella (chickenpox) vaccines

Chicken protein allergy

  • Vaccinations including the yellow fever vaccine

Lactose/milk protein allergy


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