Drug Allergy Testing

Drug allergy tests can tell you whether you are allergic to certain chemical compounds (drugs and medications), such as penicillin. Knowing whether you have a drug allergy can help you avoid medications that trigger allergy symptoms so you can avoid possible life-threatening complications like anaphylaxis.

What are the symptoms of a drug allergy?

Drug allergy symptoms can vary from mild to severe and can occur shortly after taking a medication or hours later, according to the American Academy of Allergy, Asthma, and Immunology (AAAAI). Common symptoms of a drug allergy include:

• Skin rash or hives
• Itching
• Swelling of the face, lips, tongue, or throat
• Wheezing or difficulty breathing
• Runny or stuffy nose
• Nausea, vomiting, or diarrhea
• Abdominal pain or cramping
• Anaphylaxis—a severe and life-threatening allergic reaction that can cause shock and difficulty breathing

Can you have a drug allergy without knowing it?

In some cases, a person may have a mild allergic reaction to a medication and not realize it, thinking it is just a side effect of the drug or a symptom of their underlying condition, according to the AAAAI. Repeated exposure to the drug can result in a more severe allergic reaction.

What does drug allergy testing consist of?

Drug allergy testing consists of an allergist assessing your medical history, in addition to allergy testing techniques such as:

• Skin testing
• Blood testing
• Challenge testing
• Patch testing
• Oral challenge testing

Types of drug allergy tests

Drug allergies can be diagnosed using a variety of testing techniques, including a skin test, challenge testing, or blood testing, according to the AAAAI. They also note that drug allergies can be difficult to diagnose and that your doctor will usually use drug testing in addition to other testing and obtaining a detailed medical history to make the diagnosis.

Challenge testing

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 any reaction.

Skin scratch or skin prick 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, according to the AAAAI. The AAAAI also notes that this test is only useful for diagnosing an allergy to penicillin and other drugs that contain penicillin.

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 or hand. Then, your sample is taken to a lab, where it is evaluated for allergens. According to the AAAAI, an allergy blood test usually takes less than five minutes to perform, although the results may take days to weeks.

Who should get a drug allergy test?

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

Common symptoms of drug allergies, according to the AAAAI, 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

The majority of reactions caused by medications are referred to as “adverse reactions”. The AAAAI also notes 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 the treated condition.

How to get a drug allergy test

Your doctor may refer you to an allergy specialist (allergist) if you or your doctor think you may be allergic to a drug or medication. Allergists do the necessary testing to find out whether you are allergic to one or more drugs. The AAAAI notes that an allergist can sometimes 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 AAAAI.

Another way to get a drug allergy test is to use Solv to look for 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.

What to expect during drug allergy testing

Drug allergy testing is similar to other types of allergy testing. You can expect the allergist to start by obtaining a detailed medical history and asking questions about the symptoms you experienced during the drug exposure.

How long does a drug allergy test take?

Blood tests take only a few minutes to gather a blood sample. Skin tests, challenge tests, intradermal tests, and patch tests all take varying amounts of time—however, they yield results much faster than blood tests according to the AAAAI.

Understanding your drug allergy test results

If you test positive for any part of your drug allergy test, the allergist will develop a plan to help prevent further exposure to the drug(s) you are allergic. This may include noting in your medical record to avoid receiving certain classes of medications.

Finding a drug allergy test

You can get an allergy test from a healthcare provider at a walk-in clinic or an urgent care center. Your primary care provider may refer you to an allergist, a doctor specializing in allergic disorders, when you do not respond well to treatment or if a more accurate diagnosis is necessary for management.

Solv can help you get an appointment with an allergist.

Can I get an at-home drug allergy test?

There are some at-home allergy testing kits available for purchase, however, many of these at-home tests do not test for specific drug allergies. It is best to see a medical provider if you suspect a drug allergy, according to the AAAAI.

Cost of drug allergy testing

The cost of drug allergy testing in the USA can vary widely depending on the type of test, the location, the provider, and insurance coverage. Average costs according to the Healthcare Bluebook, a website that provides estimates of fair prices for healthcare services, ranges from a couple of hundred dollars to several thousand dollars.

Drugs that commonly cause an allergic reaction

Penicillin is the most common drug allergy, says the AAAAI. They also report 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, Amoxicillin, cephalosporin, anticonvulsants, and chemotherapy drugs, adds the AAAAI.