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Was my skin allergy test a false negative? Two days later I have hives in three places where I was pricked.?
Wednesday I had a skin allergy test that came out negative. I got hives for every single prick, but they were all the same and less than the histamine control. I have urticaria/dermographism, which means I get hives for all scratches and pricks, but they usually disappear within an hour. However today, two days later, I noticed I still have hives (although not swollen) in three places where I was pricked. Is that normal or does that indicate that I might have an allergy? Has this ever happened to anyone of you before?
2 Answers
- ?Lv 76 years ago
It can be a false negative, that's not uncommon.
However, if you have dermographism, I would highly recommend exploring something called a mast cell activation disorder - the majority of people with this disorder have dermographism, and they can also often test negative to allergies even when they react.
It's considered rare, although experts are beginning to believe it's more 'rarely diagnosed' than actually rare. Most doctors wouldn't test for it, if they even knew how to do so.
This is the most up to date information on symptoms and diagnostic tests needed for it:
http://www.wjgnet.com/2218-6204/pdf/v3/i1/1.pdf
Some people get more serious symptoms, like anaphylaxis, but many do not. If you wish to talk to folks about it, Facebook has some good support groups that can help one find doctors who know about it who can test for it (literally mostly blood and urine tests, just the RIGHT ones). Search for mcad, mcas, mast cell disorder, or mastocytosis on Facebook to find 'em.
