Medication and Drug Allergies

Adverse reactions to medications are common. Allergic reactions to medications are a type of adverse reaction, specifically an IGE mediated immune response. The providers at Impact Medical can help diagnose whether you are truly allergic to a medication.

What Are Medication & Drug Allergies?

Medication allergies occur because of an immune response to a particular medication. Medications can produce a variety of immune responses leading to different types of reactions. Drug allergies can potentially be life-threatening and need to be diagnosed correctly.

Common Medication Allergies and Drug Allergic Reactions

Penicillin Allergy

Penicillin allergy is the most common medication allergy; however, 80% of patients who report a penicillin allergy are actually not allergic. It is extremely important to have the correct diagnosis, as penicillin is one of the most effective and safest families of antibiotics. Patients who are misdiagnosed are often placed on other antibiotics that are less effective or have significant side effects.

If you have a history of a suspected penicillin allergy, the doctors at Impact Medical will evaluate you via a thorough history, a blood test called ImmunoCAP testing, and standardized penicillin skin testing.

If diagnostic testing for penicillin is negative, we will then have the patient undergo a cautious graded challenge to a penicillin (or a derivative) in the office. This consists of exposing the patient to penicillin via increasing doses until a full dose is received. Patients are examined and vital signs are checked every 15-20 minutes.  The entire procedure typically is performed over 2 hours. A cautious graded drug challenge can also be performed on other types of medications, such as azithromycin, ciprofloxacin, acetaminophen, etc, in which diagnostic testing is not available. 

NSAID Allergy

NSAIDs (non-steroidal anti-inflammatory drugs) can cause a variety of reactions. NSAIDs include medications such as aspirin, ibuprofen (aka Motrin or Advil), naproxen, and many more. People with an allergy to NSAIDs can present with an increase in their asthma symptoms, hives, swelling, or a severe allergic reaction. An allergy to NSAIDs is diagnosed based on history as there is no specific skin or laboratory test to confirm the diagnosis. Typically, if a patient is allergic to one NSAID, they need to avoid the entire family of NSAIDs.

What Are Symptoms of a Medication Allergy?

Medication allergies can manifest in a variety of ways. Some of the most common symptoms include:

Rash or Hives

Raised, itchy, red patches on the skin or welts that can appear suddenly after taking a medication


Swelling or edema can occur in specific parts of the body, like the face, lips, or tongue, or it can be more generalized


A general or localized sensation of discomfort and the urge to scratch, which may or may not be accompanied by visible skin changes


An elevated body temperature may accompany an allergic reaction to medication

Upset Stomach

This can include symptoms like nausea, vomiting, diarrhea, or abdominal cramps because of the body’s adverse reaction to a drug

Shortness of Breath

Difficulty breathing, often due to the inflammation or narrowing of airways, sometimes leading to wheezing

Runny Nose or Watery Eyes

Similar to the reaction experienced with environmental allergies, some medications can cause an overproduction of mucus or tears

Dizziness or Lightheadedness

A feeling of unsteadiness or near-fainting, which could be due to the body’s response to the medication or a decrease in blood pressure

Joint Pain

Some allergic reactions to medications can manifest as joint pain or even resemble arthritic symptoms


A severe, potentially life-threatening allergic reaction that can occur rapidly. Symptoms may include difficulty breathing, a rapid or irregular heartbeat, confusion, nausea, or a drop in blood pressure

Diagnosing & Treating Drug Allergies

Medical History & Evaluation

Your allergist will begin by gathering a comprehensive medical history and performing a physical exam.

Diagnostic Testing

ImmunoCAP laboratory testing, allergy skin testing and cautious graded challenges will be recommended if indicated to confirm if one is or is not allergic to a medication.


If one is diagnosed with a medication allergy, your allergist will develop a treatment plan with a focus on avoidance.

Drug Allergy Diagnostic Testing

Explore types of allergy testing for medications below. The only medication that is able to be tested through allergy testing is penicillin.
Allergy Skin Testing
Allergy skin testing can include prick-puncture testing or intradermal skin testing to expose the skin to a small amount of the allergen to cause a reaction.
ImmunoCAP Testing
This is a blood test that detects the presence of an allergic antibody (IGE) specific to a medication.
Cautious Graded Challenge
Cautious Graded Challenge is performed in our practice’s office under close medical supervision in which the patient receives the medication in incremental doses. The patient is examined, and vital signs are checked prior to each dose. If a patient tolerates a cumulative therapeutic dose of the medication, they “pass” the challenge and are not considered allergic to the medication.

How to Treat a Medication Allergic Reaction

The treatment for a drug allergy is avoidance. In specific unusual circumstances, desensitization is possible.
Emergency Medication Treatment for Drug Allergy
If one does experience an allergic reaction to a medication, prompt medical treatment is necessary. Treatment can include the use of different medications including antihistamines, epinephrine, corticosteroids and IV fluid.

Medication & Drug Allergies FAQs

For the majority of medications, diagnostic testing is not available. Penicillin is one of the few medications for which we have standardized diagnostic testing. However, even if there is no testing available for a medication, your allergist at Impact Medical will take a detailed history and determine if it is safe to perform a cautious graded challenge to rule in or rule out a medication allergy.

Yes, outgrowing medication allergies is possible. For example, 10% of patients per year outgrow a penicillin allergy for eight years, with 20% of patients having a persistent penicillin allergy.

There is a mold called penicillium which naturally produces penicillin. If one is allergic to the mold penicillium it does not indicate a penicillin allergy.

Typically, we do not recommend taking cephalosporin if one is allergic to penicillin. Penicillin and cephalosporins both share a common structure called a Beta Lactam ring – which increases their allergic cross-reactivity. If one is allergic to penicillin, there is a 5 – 15% likelihood they will be allergic to cephalosporin.

Yes, it is possible but unlikely to be allergic to cephalosporin if you are not allergic to penicillin.

Yes. Tylenol (acetaminophen) is not in the NSAID family.

RCM contains Iodine. This is what patients react to in RCM. Iodine is often present in shellfish. Iodine sensitivity can lead to an anaphylactoid reaction, which is a non-IGE mediated response. This is not a true allergic reaction. However, patients with an iodine sensitivity can develop symptoms that mimic an allergic reaction with exposure to RCM and shellfish. Therefore, patients who are allergic to RCM should consult with an allergist at Impact Medical before eating shellfish.

This is a very common question we come across at Impact Medical. One will require a full evaluation to determine if a rash is from a medication or from the infection itself.

There are certain components of vaccines that can be tested for. For example, the MMR vaccine contains porcine gelatin which is a known allergen. Patients can be tested for an allergy to porcine gelatin.

Explore our medication & drug allergies resources today.