Is Post Nasal Drip Caused by Allergies?

Post Nasal Drip
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Post nasal drip can be caused by allergies, among other things. There are many causes of post nasal drip, or phlegm in the throat, which causes many people to frequently clear their throats. Causes of post nasal drip include allergic rhinitis, non-allergic rhinitis, and sinusitis. In addition, gastroesophageal reflux disease (GERD) may mimic post nasal drip.

Allergic Rhinitis as a Cause of Post Nasal Drip

Post nasal drip may be a symptom of allergic rhinitis, although in my opinion, it’s quite rare to have post nasal drip as the only symptom.

Typically, allergic rhinitis symptoms also include sneezing, nasal congestion, and a runny, itchy nose.

People with post nasal drip caused by allergic rhinitis are diagnosed in much the same way as those with other types of symptoms –- positive allergy testing suggests that there is an allergic cause to the symptoms, and various medicines for allergic rhinitis would likely be helpful for the treatment of post nasal drip.

Non-Allergic Rhinitis as a Cause of Post Nasal Drip

Post nasal drip may also be caused by non-allergic, or vasomotor, rhinitis. A non-allergic cause may be suspected in an older person with post nasal drip symptoms who did not have problems with allergies when they were younger.

Non-allergic triggers of post nasal drip may include worsening symptoms with weather changes, exposure to strong odors or perfumes, or as a result of taking various medicines for high blood pressure.

By definition, people with non-allergic rhinitis show no reactions on allergy testing.

Treatments for non-allergic post nasal drip include nasal steroids, nasal antihistamines, anticholinergic nasal sprays (such as iptratropium bromide) and older oral antihistamines, such as Benadryl (diphenhydramine) or ChlorTrimeton (chlorpheniramine), used for their drying side effects.

Sinusitis as a Cause of Post Nasal Drip

Post nasal drip may also be the only symptom of sinusitis (sinus infection), or it may go along with other symptoms, such as facial pain, nasal congestion and colored nasal discharge. When post nasal drip is the only symptom of a sinus infection, it is usually because the infection is a low-grade “smoldering” infection that has been going on for months, and sometimes even for years. Because the symptoms of these types of sinus infections are so mild, a diagnosis is often only made after a sinus x-ray is performed.

Post nasal drip caused by a sinus infection is treated with antibiotics, although the antibiotics may need to be taken for a longer period of time if the infection is thought to be chronic (lasting for more than 2 months or an infection that keeps coming back).

Gastroesophageal Reflux Disease as a Cause of Post Nasal Drip

While GERD does not cause post nasal drip, it may mimic the symptom. The diagnosis of GERD may be made using direct laryngoscopy, which may show irritation in the upper throat from stomach acid; with a 24-hour pH probe; or with esophagogastroduodenoscopy.

The treatment of GERD most commonly includes the use of proton pump inhibitors for many months.


Wallace DV, Dykewicz MS, chief editors. The Diagnosis and Management of Rhinitis: An Updated Practice Parameter. J Allergy Clin Immunol. 2008;122:S1-84.

Buttram J, More D, Quinn J. Allergy and Immunology. The Complete History and Physical Exam Guide. 2003:53-69.

Bousquet J, van Cauwenberge P, Khaltaev N. Allergic Rhinitis and Its Impact on Asthma. J Clin Allergy Immunol. 2001;108:S147-344.

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