How an Allergist Will Test For Ragweed Allergy

Published: September 2, 2020

Ragweed allergy

Q: Given her symptoms in the fall, I suspect my daughter has a ragweed allergy. How can we test for this?

Dr. Bassett: The quickest and most sensitive way an allergist tests for a ragweed allergy is via the skin. A skin test involves a slight prick to expose the patient to a small amount of diluted ragweed pollen and other allergens. After 15 to 20 minutes, the allergist evaluates the size and redness of the resulting “wheal” or elevated bump.

When a skin test is negative, but an allergy is still suspected, sometimes a more sensitive intradermal test is done, with an allergen injection given just below the skin’s surface.

Skin testing requires the patient to stop taking antihistamines. A blood test that measures IgE antibodies to ragweed and/or weed pollens doesn’t require this, and can be used to assess possible allergies. The laboratory will provide results within several days.

If the ragweed allergy is confirmed, the allergist will recommend starting OTC medications (such as antihistamines, eye drops, and nasal sprays) before the allergy season begins.

Avoidance measures are definitely helpful, such as using your air conditioner to filter out unwanted pollen. Showering before bedtime can also prevent accumulated pollen from transferring to the pillow.

For the long term, discuss with the allergist whether your child is a candidate for allergy shots or sublingual (under-the-tongue) therapy.

Dr. Clifford Bassett, allergist and asthma specialist, is the Medical Director of Allergy & Asthma Care of New York (; Twitter @allergyreliefny). He is on the faculty of NYU School of Medicine and Weill Cornell Medical College in New York City and is also the author of The New Food Allergy Solution.

Related Reading:
How to Control Asthma Symptoms During Ragweed Season
All About Ragweed Allergy: Signs, Symptoms and Avoidance
Finding Pollen Allergy Relief: What Pill, Spray or Shot is Right?

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