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Antihistamine and RAST Test-how long without??

3 replies [Last post]
By maddiesmom on Sat, 06-10-06, 12:53

Good morning! Well, I had planned on taking both my kids for their RAST test this morning at the outpatient lab at the Hospital but now we may have to wait....need some help from all of you!

Yesterday a.m. my son received his daily dose of Claritin for his seasonal allergies. I seem to recall my allergist telling me years ago that they cannont have any antihistamine's in their system or the RAST test will be null/void. BUT, I don't remember how long it has to be out of their system? A day? A week? My 7yr old DD is also getting her RAST done and she recieved Benedryl on Thursday due to a hives outbreak at school from peanut/nut traces. SOOOO...should I wait to take them?? Or can I still go today??

I called my Pediatritions office, because Allergist is closed on Saturday, and they had NO IDEA. I called the QUEST LAB at the hospital, they didn't know either. They transferred me to the Chemistry Lab to talk to a Chemist and he didn't know either! AUGHHHH> So frustrating!!!

If any of you know the protocol for how long without antihistamine before a RAST test, it would be very helpful. I would love to take them today, if I could, while Hubby is home to help.

(mom to 7 yr old DD pn/tn/soy and 4 yr old no allergies????)

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By DRobbins on Sat, 06-10-06, 13:31

There's no problem taking antihistamines and doing the blood draw for the RAST tests as far as I know. You can't be on antihistamines for several days to a week (depending on the type of antihistamine) before doing skin testing, but according to my kids' pediatrician, my PA son's allergist, and my own allergist, antihistamines will not alter the results of a RAST test.


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By that'smetrying on Sat, 06-10-06, 15:46

ditto. For the RAST you do not need to go off meds, only for the scratch tests.

mom to Ari(6) - severe nut allergies, asthma, you name it - and Maya (8), mild excema

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By maddiesmom on Sat, 06-10-06, 19:31

Thank you both! We went this morning after getting your responses and it went SOOOO well. Both kids were great, no tears or fights about it. AMAZING! It wasn't this easy last time! Even the 4 year old didn't cry he just wanted to know when he will get his blood back! [img]http://uumor.pair.com/nutalle2/peanutallergy/smile.gif[/img]

Thank you for your help.
Love this site!

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