If it's allergy related you can take Claritin... Or however it is spelled. If it's cold related really you can only take Tylenol cold and flu. Web MD has a list... Here is the link
http://www.m.webmd.com/baby/guide/taking-medicine-during-pregnancy?page=2
My doctor only let me take robitusin cough and chest congestion but it depend on how far along you are, i was in my first trimester, you may be able to take something else if your in your third
I have a whole pregnancy medicine list at home. When I get home, I'll let you know what's safe :)