Drug Allergy Testing

Drug allergy testing is generally recommended for anyone who thinks they may be allergic to a drug. If you are allergic to a drug, you will experience allergy symptoms when using that drug, or when using medications that include that drug as an ingredient.

Common symptoms of drug allergies, according to the Asthma and Allergy Foundation of America (AAFA), are:

• Hives
• Wheezing
• Shortness of breath
• Swelling of the mouth and throat
• Nausea
• Vomiting
• Diarrhea
• Abdominal cramping and pain
• Lowered blood pressure
• Fainting
• Anaphylaxis
• Anemia

According to the AAFA, the majority of reactions caused by medications are more commonly referred to as “adverse reactions to drugs.” It adds that there are two main categories of adverse reactions to drugs: a true allergic reaction that involves the immune system and Immunoglobulin E (IgE) antibodies and non-allergic reactions.

True allergic reactions occur in only a small percentage of people. Examples of adverse reactions to drugs that are not considered true allergic reactions include expected (known) side effects, overdosing, and worsening of a known condition, adds the AAFA.

Inform your doctor right away if you are experiencing one or more symptoms of drug allergies when using a medication. Your doctor may suggest getting an allergy drug test so you can get closer to receiving a proper diagnosis.

Your doctor may refer you to an allergist if you think you may be allergic to a drug or medication. An allergist is a doctor who specializes in allergies, says the AAFA. Allergists can do the necessary testing to find out whether you are allergic to one or more drugs. It adds that an allergist can make a clinical diagnosis based only on your medical history and symptoms.

If you are experiencing an allergic reaction and take multiple drugs or medications at the same time, it may be difficult for the allergist to identify which drug is causing your symptoms. In that case, the allergist may recommend stopping one or more drugs until the allergen is confirmed, reports the AAFA.

Another way to get a drug allergy test is to use Solv to look for testing providers, or allergists, in your local area. Solv features a directory of only the highest-rated providers and allows you to browse patient reviews and book an appointment with no phone call necessary.

Drug allergies can be diagnosed with a skin test, drug challenge, or blood test, says the American College of Allergy, Asthma, and Immunology (ACAAI). It adds that drug allergies can be difficult to diagnose and that your doctor may ask a series of questions to identify the cause of your symptoms. For instance, your doctor may ask when your symptoms began, which drug you think is causing them, and whether you also take any herbal or nutritional supplements, adds the ACAAI.

The ACAAI reports that a skin test is only useful for diagnosing an allergy to penicillin and other drugs that contain penicillin. It adds that a blood test is usually only used in instances when you are experiencing a severe or delayed reaction to a drug or medication. In all other instances, drug allergy tests are usually performed as drug challenges.

According to the AAFA, tests are only available for a small number of drugs that cause people to experience allergic reactions. It adds that the test for penicillin allergy is one of the most reliable drug allergy tests available.

During a drug challenge, you will be given the drug or medication suspected of triggering an allergic reaction. Then, you will be closely monitored by medical staff for a reaction.

Skin tests

Allergy skin tests can be performed as a scratch test—also known as a spin prick test—or as an intradermal test, says the National Library of Medicine (NLM).

Scratch tests

During a scratch test, your provider will place small amounts of the suspected drugs on different areas of your skin. Then, your provider will lightly scratch or prick your skin where the drugs were placed. If you are allergic to any of the drugs, a small red bump will show up on your skin within 15 to 20 minutes, reports the NLM.

Intradermal tests

The intradermal test is usually only performed when a scratch test is negative, but your provider still thinks you may be allergic to a drug. During an intradermal test, a small amount of the drug is injected into your skin using a small, thin needle. Then, your provider will watch the injection site for an allergic reaction.

Blood tests

An allergy blood test is performed like any other routine blood test. During this test, your provider will use a small, thin needle to draw a small amount of blood from a vein in your arm. Then, your sample is taken to a lab, where it is evaluated for allergens. According to the NLM, an allergy blood test usually takes less than five minutes to perform.

Penicillin is the most common drug allergy, says the ACAAI. It adds that if you have an allergic reaction after taking penicillin, it doesn’t necessarily mean you will have a similar reaction to another antibiotic that contains penicillin—such as amoxicillin—but it is more likely to happen.

Other drugs that commonly cause allergic reactions include aspirin, ibuprofen, anticonvulsants, and chemotherapy drugs, adds the ACAAI. Amoxicillin and cephalosporin are other drugs that may cause allergic reactions, according to the NLM.