Need to see a doctor for the flu. If its a little cold, nothing. I had a terrible sinus infection in my first trimester and was only allowed to take mucinex. It actually made it worse... All medication you take during pregnancy should be discussed with a doctor anyways, we are not medically trained, just a support susptem for mommies.
Are you sure it's the flu you have? Cause if it is you should probably go see your doctor. Flu can be dangerous for pregnant women. If it's just a regular cold, there's not much you can take. I had a bad cold around 22 weeks and I took hot showers, drank tons of water and orange juice, ate some cough drops, and rested. We're limited on medications we can take so if it's the flu and you have a fever, call your doc.