I was going to say Benadryl Allergy is safe as I was taking that for my nausea and vomiting but it turns out it is a Category B drug. I googled allergy medicines in pregnancy and came up with a ninemsn health article that had this

Included in Category A "Drugs which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the foetus being observed" are the following antihistamines: brompheniramine, chlorpheniramine, clemastine, cyproheptadine, dexchlorpheniramine, diphenhydramine, diphenylamine, doxylamine, pheniramine, triprolidine, chlorcyclizine, cyclizine and hydroxyzine. However, these are antihistamines of the older type, which cause sedation. This is can be a problem with driving, operating machinery and simply being able to function optimally.
Maybe just google the drug name to find out the brand names or take the list to the chemist and make them do the work. Good luck, hayfever is not fun, luckily I don't suffer as much as I used to.