How Prednisone Can Affect Your Allergy Test Results

If you’re preparing for allergy testing, some medications can interfere with your results. Antihistamines and certain allergy, cold, and sinus medications may reduce your skin’s response during testing, making it important to know what to stop—and when—before your appointment.

As a general guideline, patients may be asked to stop oral antihistamines and certain over-the-counter allergy, cold, and sinus medications at least five days before skin allergy testing. Other medications, including corticosteroids such as prednisone, may require different instructions.

In this article, Boulder Medical Center board-certified allergists Katherine McCormack, MD, and Karen Andrews, MD, explain which medications can affect allergy skin testing, how long before testing they may need to be stopped, and what to know about prednisone and allergy testing. Always follow your allergist’s specific instructions before changing or stopping any medication.

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 show up on 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, doctors most commonly recommend stopping prednisone 1 to 2 weeks before testing, but your doctor may recommend something different 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 helps ensure the most accurate and helpful results for managing your allergies effectively.

Resources

BMC Allergy, Asthma & Immunology provides testing, diagnosis, and treatment for adults and children in Boulder and Louisville. Learn more about our allergy, asthma, and immunology services and how to schedule an appointment.