By Katie McCormack, MD, and Karen Andrews, MD
Board-Certified Allergists, Boulder Medical Center (Boulder & Louisville, CO)
Understanding how medications affect your results is essential if you’re preparing for allergy testing. Allergy testing helps identify triggers like pollen, pet dander, or certain foods—common concerns in our region’s seasonal and environmental allergy landscape.
As a general rule, stop all oral allergy, cold, and sinus medications at least five days before your skin test appointment. This includes over-the-counter (OTC) medications, antihistamines, and herbal supplements that may interfere with test results. Boulder Medical Center allergists provide the list below to help patients know which medications to stop—and when—before their appointment. Be sure to consult your allergist for any personalized recommendations.
This article focuses on prednisone, a corticosteroid commonly prescribed to reduce inflammation and suppress the immune system. It treats conditions ranging from asthma and allergic reactions to autoimmune diseases.
BMC list of medications to stop before allergy testing
How Prednisone Affects Allergy Testing
Allergy tests, particularly skin prick tests, rely on your immune system’s response to allergens introduced to the skin. Prednisone, however, suppresses that immune response, which can dampen or completely block the skin’s reactivity. This can lead to false-negative results, where an allergy is present but doesn’t appear in testing.
Prednisone has a less immediate effect on blood tests (such as specific IgE testing), but long-term use can still influence immune markers and overall results.
How Long to Wait Before Testing
For skin tests, it’s most commonly recommended to stop prednisone one to two weeks before testing, but your doctor may have other recommendations depending on the dose and duration of use. Always consult your allergist before stopping any medication—discontinuing steroids abruptly can have serious health consequences.
Let Your Provider Know
If you’re scheduled for allergy testing in Boulder or Louisville, let your healthcare provider know if you’re taking prednisone or other immunosuppressive drugs. Timing your test appropriately ensures you get the most accurate and helpful results for managing your allergies effectively.
Resources
The board-certified Allergy, Asthma, and Immunology team at Boulder Medical Center (BMC) treats children and adults at Boulder and Louisville, Colorado clinics. The group serves patients throughout Boulder County and nearby communities, including Lafayette, Superior, Erie, Longmont, Broomfield, and more.
Learn more about BMC’s Allergy, Asthma & Immunology services