Medications that can interfere with allergy testing

November 27, 2001

You'll need to follow the directions given by your physician or his nurse, Physicians may differ in their recommendations. But I think the way we do it in our office is fairly close to what most allergists recommend.

We ask our patients to stop antihistamines 48 hours prior to testing. When you have an allergic reaction, your body releases histamine. Histamine causes allergic symptoms such as rashes or runny nose and eyes.

Antihistamines* don't get rid of the allergy, they just intercept the histamine to block the symptoms. When you are tested for allergies, we look for a skin weal or bump in response items you are allergic to. If the antihistamine blocks this skin reaction, the allergy won't show up.

Some antidepressants** can block results from allergy testing also. If your allergist says your antidepressant may interfere with testing, ask the physician who prescribed the antidepressant for you if you can stop it for a couple of days. Do not stop your antidepressant without your doctor's guidance.

You will need to talk with your physician if you are taking a beta blocker*** medication. Beta blockers make it difficult to reverse a systemic reaction to testing or shots. Don't try to stop the beta blocker on your own.

You shouldn't stop any of your routine medications without your physician's recommendations. We've had to send patients home to take their blood pressure meds prior to testing because their blood pressure was dangerously high. If you stop all meds "just in case," you may make testing unsafe.

*For a list of antihistamines, click here.

**A local pharmacist worked with me to research antidepressants that are likely to interfere with allergy testing. See the list here.

***For a list of beta blockers click here.

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