Causes

• Post-nasal drip is not an illness itself but rather a symptom of upper respiratory infections or irritation. Some of the causes of nasal or sinus discharge, which may manifest in a variety of ways, including post-nasal drip, are colds, influenza, sinusitis, hay fever, bacterial infections and nasal sprays, according to MedlinePlus. The condition also can be triggered when foreign objects become lodged in the nostrils of small children.
  
  

Why the Mucus?

• Even in the absence of an infection or irritating allergen, the glands of the nose and throat produce mucus to clean and moisten nasal membranes; trap and help to clear foreign matter; fight infection; and humidify the air you breathe, according to the American Academy of Otolaryngology (AAO). Each day, somewhere between one and two quarts of this mucus is produced. These mucosal secretions ordinarily are swallowed without any ill effects or discomfort. However, post-nasal drip occurs when you have a sensation of mucosal buildup that tickles or irritates the throat, which is usually an indication that the secretions are abnormally thick.
  
  

What You Can Do

• If you're uncertain about the root cause of your post-nasal drip but want to take steps to ease the symptoms, you may be able to thin out the mucosal secretions by increasing your intake of fluids. The AAO also suggests that you use mucus-thinning agents, such as guaifenesin, which can be found in Robitussin and Humibid, as well as frequent nasal irrigation with a solution of baking soda or salt in warm water (one to one-half teaspoon per pint). It would also be a good idea to avoid caffeine and diuretics until your symptoms have eased.
  
  

Medications

• If your doctor has diagnosed the illness that is responsible for your post-nasal drip symptoms, he will prescribe appropriate medications to treat that underlying condition, thus easing the nighttime discomfort. If you suspect that increased nasal or sinus discharge is caused by allergies, you probably can find some relief by using over-the-counter medications to counter the effects of allergic reactions. The active ingredient in most such drugs is a type of antihistamine, so be careful to read warnings on the drug's packaging to ensure that the medication is appropriate for you.
  
  

Antibiotics Not a Cure-All

• Unless your doctor definitively diagnoses a bacterial infection as the cause of your post-nasal drip, antibiotics will provide no help in easing your condition. Colds and flu, two of the more common causes of post-nasal drip, are both cause by viral agents, meaning antibiotics would not be effective.