Allergies Nose & Eye Allergies Possible Causes of Post-Nasal Drip By Daniel More, MD Daniel More, MD Daniel More, MD, is a board-certified allergist and clinical immunologist with a background in internal medicine. Learn about our editorial process Updated on February 10, 2022 Medically reviewed by Farah Khan, MD Medically reviewed by Farah Khan, MD LinkedIn Farah Khan, MD, is a board-certified allergist/immunologist who treats pediatric patients at Nationwide Children's Hospital in Columbus, Ohio. Learn about our Medical Expert Board Print Table of Contents View All Table of Contents Allergic Rhinitis Non-Allergic Rhinitis Sinusitis Rhinitis Medicamentosa Hormones The main symptom of post-nasal drip is the feeling of having phlegm in the back of your throat. There are several different conditions that can result in the same symptom, and determining the cause is the best way to make sure you receive the best treatment. RunPhoto/Getty Images There are many causes of post-nasal drip, or phlegm in the throat. They include: Allergic rhinitis (hayfever)Non-allergic rhinitis (vasomotor rhinitis)SinusitisOveruse of nasal sprays such as AfrinHormonal causes such as pregnancy or hypothyroidism Despite the variety of causes, the symptoms are similar (e.g., frequent need to clear the throat). Allergic Rhinitis Post-nasal drip may be a symptom of allergic rhinitis (hayfever), although it’s quite uncommon 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 symptoms. Positive results on allergy testing suggest that there is an allergic cause to the symptoms. Having a good response to treatment with medicines for allergic rhinitis also increases the chance that post-nasal drip is related to hayfever. Non-Allergic Rhinitis Post-nasal drip may also be caused by non-allergic rhinitis, 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: Weather changes Exposure to strong odors or perfumes Eating spicy foods (gustatory rhinitis) Medicines for high blood pressure (medication-induced rhinitis) Exercise, sex (exercise-induced rhinitis) By definition, people with non-allergic rhinitis show no reactions to allergy testing. Treatments for non-allergic post-nasal drip include nasal steroids, nasal antihistamines, anticholinergic nasal sprays (such as ipratropium bromide) and older oral antihistamines, such as Benadryl (diphenhydramine) or Chlor-Trimeton (chlorpheniramine), used for their drying side effects. Sinusitis Post-nasal drip may also be the only symptom of sinusitis (infectious rhinitis), 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 infection that has been going on for months—and sometimes even years. Because the symptoms of these types of sinus infections are so mild, a diagnosis is often only made after a computed tomography (CT) scan 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-than-typical period of time if the infection is thought to be chronic (lasting for more than two months or keeps coming back). Rhinitis Medicamentosa Rhinitis medicamentosa is a complicated way to describe the type of a runny nose and congestion that occurs when a person has been overusing a medication like Afrin (oxymetazoline). As the body adapts the medication, more and more of the medication is needed. Severe post-nasal drip may occur until the cycle is broken. Hormonal Causes Pregnancy-induced rhinitis, or hormonal rhinitis, is a common cause of post-nasal drip in those who are pregnant. Symptoms usually begin during the second trimester and persist until delivery, resolving shortly after the baby is born. For others, hormonal rhinitis may occur with the use of birth control pills or when thyroid function is low (hypothyroidism.) Could It Be GERD? While gastroesophageal reflux disease (GERD) does not cause post-nasal drip, it can cause the same sensation. If you have what seems to be post-nasal drip without a confirmed cause, see your healthcare provider. This is especially important if you have accompanying symptoms such as heartburn, chest discomfort, or abdominal pain. Not only does having reflux affect your quality of life, but it can have health complications. A Word From Verywell There are many causes of post-nasal drip. Some of them may be identified after reviewing your history, such as your symptoms, response to treatments tried, and when your postnasal drip occurs. An examination of the consistency of the drainage (thinner with allergic and non-allergic rhinitis, thicker with sinusitis) can also be revealing. While you may have learned to live with your post-nasal drip, it is best to be evaluated by a healthcare provider so you can get a proper diagnosis and the most effective treatment. Post-nasal drip can impact your quality of life as well as your performance at work or school. 9 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Yu JL, Becker SS. Postnasal drip and postnasal drip-related cough. Curr Opin Otolaryngol Head Neck Surg. 2016;24(1):15-19. doi:10.1097/MOO.0000000000000226 Varshney J, Varshney H. Allergic rhinitis: an overview. Indian J Otolaryngol Head Neck Surg. 2015;67(2):143-149. doi:10.1007/s12070-015-0828-5 Pinto JM, Jeswani S. Rhinitis in the geriatric population. Allergy Asthma Clin Immunol. 2010;6(1):10. doi:10.1186/1710-1492-6-10 Bhargava D, Bhargava K, Al-Abri A, Al-Bassam W, Al-Abri R. Non allergic rhinitis: prevalence, clinical profile and knowledge gaps in literature. Oman Med J. 2011;26(6):416-420. doi:10.5001/omj.2011.106 Kaliner MA. Classification of nonallergic rhinitis syndromes with a focus on vasomotor rhinitis, proposed to be known henceforth as nonallergic rhinopathy. World Allergy Organ J. 2009;2(6):98-101. doi:10.1097/WOX.0b013e3181a9d55b Scarupa MD, Kaliner MA. Nonallergic rhinitis, with a focus on vasomotor rhinitis: clinical importance, differential diagnosis, and effective treatment recommendations. World Allergy Organ J. 2009;2(3):20-25. doi:10.1097/WOX.0b013e3181990aac Morice AH. Post-nasal drip syndrome--a symptom to be sniffed at? Pulm Pharmacol Ther. 2004;17(6):343-345. doi:10.1016/j.pupt.2004.09.005 Kariyawasam HH, Scadding GK. Chronic rhinosinusitis: therapeutic efficacy of anti-Inflammatory and antibiotic approaches. Allergy Asthma Immunol Res. 2011;3(4):226-235. doi:10.4168/aair.2011.3.4.226 Dzieciolowska-Baran E, Teul-Swiniarska I, Gawlikowska-Sroka A, Poziomkowska-Gesicka I, Zietek Z. Rhinitis as a cause of respiratory disorders during pregnancy. Adv Exp Med Biol. 2013;755:213-220. doi:10.1007/978-94-007-4546-9_27 Additional Reading Kasper DL, Fauci AS, Hauser SL. Harrison's Principles of Internal Medicine. New York: Mc Graw-Hill Education; 2015. Kliegman RM, Stanton BF, St Geme III JW, Schor NF, Behrman RE, Nelson WE. Nelson Textbook of Pediatrics. 20th Edition. Philadelphia, PA: Elsevier; 2015. MedlinePlus. Allergic rhinitis. Updated June 9, 2021. By Daniel More, MD Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California. See Our Editorial Process Meet Our Medical Expert Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit