What medicine is good for allergy?

Depends: This is an open question, more information is needed.

There are many: There are quite a few anti-histamine/allergy medications over-the-counter. Some have decongestants with them, some are just anti-histamines. The newer ones like Loratadine (claritin), fexofenadine (allegra), and ceterizine (zyrtec) and less sedating, but seem less effective than the older medications such as diphehydramine (benadryl), chlor-trimeton, etc. By trying them, you'll see which work.