Drug Allergy & Allergic Reactions to Medications Feature Image

Drug Allergy & Allergic Reactions to Medications

Any medication could potentially cause an allergic reaction. The drug that causes the most reactions is penicillin, affecting up to 10% of the population. Other drugs that trigger allergies include sulfa drugs, anticonvulsants, nonsteroidal anti-inflammatory drugs (aspirin), and chemotherapy drugs.

Allergic reactions to drugs or medications usually do not occur the first time a person takes a specific drug. You may have been exposed to the medication or a medication in the same drug class without knowing it. It is important to identify a drug allergy because the symptoms can be very uncomfortable or even life-threatening:

Drug Allergy Symptoms

It is possible that what you think may be a drug allergy could actually be drug interactions or side effect.  For this reason, it is very important to make sure you tell your NY doctor about all of the medications you have been taking. Common side effects that are not allergic reactions include:

  • Diarrhea
  • Dry mouth
  • Headaches
  • Heartburn
  • Racing heart

Because these reactions can be complicated, it is very important for you to seek medical attention quickly.  The allergy and asthma physicians at NY Allergy & Sinus Centers will help figure out what is an allergic reaction, as opposed to a side effect of a medication. Allergic reactions can be very dangerous and a NYASC allergy doctor can assist you in identifying the symptoms of allergies.

Diagnosing A Drug Allergy

A skin prick test can diagnose a penicillin allergy; however, it’s not accurate for other drugs. Drugs that are injected can be diagnosed by intradermal testing. During this test, an allergist will introduce the allergen beneath the skin and watch for a reaction. Intradermal testing is more sensitive than skin prick testing, so allergic reactions can be severe. Your doctor will have epinephrine and other allergy medications available to treat any symptoms.

In addition, a drug challenge may be performed. A dose of the suspected allergen may be administered in the office under careful observation to confirm the allergy. This is done only as a last option, as some drugs are known to cause severe allergic reactions.

Drug Allergy Treatment

Many drug allergies disappear over time. For those that don’t, desensitization is a treatment option. Desensitization is available for penicillin, aspirin, and some chemotherapeutic drugs. The process involves gradually administering the medication by mouth or as shots to build tolerance of the drug. This treatment is only necessary for patients with ongoing medical conditions who  require certain medications where there aren’t any alternatives.

When possible, avoidance is always the best treatment for allergies. Ask your doctor about alternatives to the drugs you are allergic to. There are usually many options of medications to treat your condition.

Drug Allergy Frequently Asked Questions

How Do I Know if I’m Allergic to Medication or Just Experiencing a Side Effect?

You should seek medical attention immediately if you experience any physical reaction after taking medication.

If I Have a Reaction to a Drug Once, Does That Mean I Have to Stop Taking it Completely?

If you have been diagnosed with a drug allergy, you should avoid the drug that caused the reaction. However, you should get allergy tested regularly to determine if your sensitivity has disappeared.

How Long Does Desensitization Last?

The process typically takes 2 days, however, it can take longer for some patients.

Does Desensitization Work for Every Drug?

No, the process is not available for every drug.


If you think you may have an allergy to medication, the NYC allergists of NY Allergy & Sinus Centers are here to help.  We have access to the latest testing & treatments & we offer convenient asthma and allergy clinics throughout NYC. Call us today at 212-686-4448 to make an appointment. We see both adult and pediatric patients.