WebMD states that postnasal drip caused by a bacterial infection is treated with antibiotics. Antihistamines, decongestants and thinning the mucus help with postnasal drip caused by viral infections and sinusitis, and the reduction of allergy triggers treat postnasal drip caused by allergies.
According to WebMD, over-the-counter antihistamines, such as Benadryl, are sometimes not as effective as Clarinex, Xyzal and Allegra since Benadryl can sometimes thicken mucus by drying it. Clarinex, Xyzal and Allegra are more effective antihistamines that are also less likely to cause drowsiness, and medicines such as Mucinex, known generically as guaifenesin, effectively thin out mucus in the sinuses.
Saline nasal sprays and nasal irrigation also remedy postnasal drip by flushing out mucus, bacteria and other irritants in the sinuses, and a humidifier or vaporizer lessens postnasal drip by increasing moisture in the air. WebMD suggests washing bedding in hot water often and utilizing dust-proof covers to reduce allergy triggers that cause postnasal drip. Using HEPA air filters along with dusting and vacuuming regularly further reduces the allergy triggers that cause postnasal drip. Propping pillows under the head while sleeping prevents postnasal drip by reducing the amount of mucus that collects in the back of the throat overnight.