Thanks for your query.
From your history it seems to me you are suffering from urticaria
though your palm is needed to be examined properly. Benadryl will not give you relief for your condition. If it is a spot only on your palm with itghing and pain on pressure then chance of being urticaria is very high. Though i must advise you to consult a dermatologist
to get examined properly to exclude palmar space infection. If it is urticaria then i will suggest you to take antihistaminic like hydroxyzine
and levocetrizine daily along with H2 blocker like ranitidine
. Hydroxyzine 25 mg thrice daily with ranitidine 150 mg twice daily will be of help if its urticaria. But you should start these drugs only after consulting a dermatologist in order to get examined. Hope my advice will be of help to you.
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