A thorough exam and appropriate diagnostic tests are essential for an accurate diagnosis. Research has suggested that drug allergies may be overdiagnosed and that patients may report drug allergies that have never been confirmed. Misdiagnosed drug allergies may result in the use of less appropriate or more expensive drugs.
Your doctor will conduct a physical examination and ask you questions. Details about the onset of symptoms, the time you took medications, and improvements or worsening of symptoms are important clues for helping your doctor make a diagnosis.
Your doctor may order additional tests or refer you to an allergy specialist (allergist) for tests. These may include the following.
With a skin test, the allergist or nurse administers a small amount of a suspect drug to your skin either with a tiny needle that scratches the skin, an injection or a patch. A positive reaction to a test will cause a red, itchy, raised bump.
A positive result almost always indicates a drug allergy. A negative result is more difficult to interpret because of differences in the reliability of tests. For some drugs, a negative test result usually means that you're not allergic to the drug. For other drugs, a negative result may not rule out the possibility of a drug allergy.
Your doctor may order blood work to rule out other conditions that could be causing signs or symptoms.
While there are blood tests for detecting allergic reaction to a few drugs, these tests aren't used often because of the relatively limited research on their accuracy. They may be used if there's concern about a severe reaction to a skin test.
Results of diagnostic workup
When your doctor analyzes your symptoms and test results, he or she can usually reach one of the following conclusions:
- You have a drug allergy
- You don't have a drug allergy
- You may have a drug allergy — with varying degrees of certainty
These conclusions can help your doctor and you in making future treatment decisions.
Oct. 10, 2014
- Joint Task Force on Practice Parameter. Drug allergy: An updated practice parameter. Annals of Allergy, Asthma & Immunology. 2010;105:259.
- Drug reactions and drug allergies. American College of Allergy, Asthma & Immunology. http://www.acaai.org/allergist/ALLERGIES/TYPES/DRUG-ALLERGY/Pages/default.aspx. Accessed July 22, 2014.
- Drug hypersensitivity. The Merck Manual for Health Care Professionals. http://www.merckmanuals.com/professional/immunology_allergic_disorders/allergic_autoimmune_and_other_hypersensitivity_disorders/drug_hypersensitivity.html?qt=drug sensitivity&alt=sh. Accessed July 22, 2014.
- Chiriac AM, et al. Drug allergy diagnosis. Immunology and Allergy Clinics of North America. 2014;34:461.
- Romano A, et al. Antibiotic allergy. Immunology and Allergy Clinics of North America. 2014;34:489.
- Anaphylaxis. The Merck Manual for Health Care Professionals. http://www.merckmanuals.com/professional/immunology_allergic_disorders/allergic_autoimmune_and_other_hypersensitivity_disorders/anaphylaxis.html?qt=anaphylaxis&alt=sh. Accessed Aug. 10, 2014.
- Adkinson NF, et al. Middleton's Allergy: Principals and Practice. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2014. http://www.clinicalkey.com. Accessed July 22, 2014.
- Young JS, et al. Chemotherapeutic medications and their emergent complications. Emergency Medicine Clinics of North America. 2014;32:563.
You Are ... The Campaign for Mayo Clinic
Mayo Clinic is a not-for-profit organization. Make a difference today.