If the cause of your sinus infection is seasonal allergies such as exposure to pollen, mites, dust, pet hair and the likes, antihistamines may help the problem. However, the constant use of antihistamines can lead to drying up of the sinuses and slow down the draining process. It is not advisable to take histamines without a doctor prescription. Consult with a doctor to diagnose if your sinus infection is being caused by exposure to allergens, your doctor may conduct a patch test or other diagnosis to determine the root cause and recommend the best course of action.