What kind of allergies cause post nasal drip

What kind of allergies cause post nasal drip

Postnasal drip is a common occurrence, affecting almost everyone at some point in their lives. The glands in your nose and throat continually produce mucus to:

  1. fight infection
  2. moisten nasal membranes
  3. filter out foreign matter

You typically swallow the mucus without even realizing it.

When your body starts producing additional mucus, you might feel it accumulate in the back of your throat. You may also feel it dripping below your throat from your nose. This is called postnasal drip.

Common symptoms of postnasal drip include:

  1. a cough that’s worse at night
  2. sore, scratchy throat
  3. nausea from excess mucus moving into your stomach
  4. feeling that you need to constantly clear your throat or swallow
  5. bad breath

Post-nasal drip symptoms

Symptoms that may be associated with post-nasal drip (the feeling of mucus running below the back of your throat) include:

  1. the need to clear the throat often;
  2. a blocked or runny nose; and (rarely)
  3. a ‘tickle’ in the throat or sore throat;
  4. excess mucus (phlegm) in the throat;
  5. cough;
  6. hoarseness or wheezing when breathing in.

Post-nasal drip can also cause bad breath (halitosis).

Symptoms of upper airway cough syndrome include:

  1. a dry cough that persists for 8 weeks or more;
  2. post-nasal drip; and
  3. abnormal, unpleasant sensations in the throat (such as the feeling of something being stuck in the throat, something tickling or irritating the throat, or of mucus in the throat).

Tests and diagnosis

Your doctor will enquire about your symptoms and examine your nose and throat.

Post-nasal drip is often diagnosed based on your symptoms (after other possible diagnoses own been ruled out).

Your doctor may recommend allergy testing if hay fever is considered to be causing your symptoms and you do not know what you are allergic to. This may involve skin prick tests or allergy blood tests.

Other tests that may be suggested include a chest X-ray, lung function tests and blood tests such a full blood count. A CT scan of the nose and sinuses is occasionally recommended to confirm a diagnosis of sinusitis.

If you own persistent or difficult-to-treat symptoms, your doctor may refer you to an ear, nose and throat (ENT) specialist for further assessment and treatment.

The specialist may recommend nasal endoscopy, where a special instrument with a camera is used to examine the inside of the nose and throat. This test can assist diagnose nasal polyps and other problems in the nose and throat.


Medicines and treatments will vary depending on the cause (or suspected cause) of your post-nasal drip. Always check with your doctor or pharmacist before taking any over-the-counter medicines, and enquire about the possible side effects.

Allergic rhinitis

If allergic rhinitis is thought to be the cause of your post-nasal drip, antihistamine medicines will generally be recommended.

These medicines can be taken as tablets or nasal sprays. A response to treatment helps confirm the diagnosis.

A nasal corticosteroid spray or a medicine called montelukast may also be recommended for allergic rhinitis. Montelukast (taken as tablets) is a leukotriene receptor antagonist – these medicines are also used to treat asthma.

Sometimes, decongestant nasal sprays or tablets may be recommended if other medicines own not relieved the symptoms.

However, there are some risks with these medicines and they should only be used for a short time.

What helpful of allergies cause post nasal drip

In fact, overuse of nasal decongestant medicines can actually make symptoms worse, so don’t use them for more than a few days at a time.

If your post-nasal drip is due to allergic rhinitis and the allergen cannot easily be avoided or if the allergy symptoms are particularly severe and persistent, immunotherapy treatment might be recommended. This therapy is often extremely effective in desensitising people against specific allergens.


Rhinosinusitis can be treated with a saline nose spray or saline washouts (nasal irrigation).

Most acute cases of rhinosinusitis (those that come on quickly and don’t final long) are caused by a viral infection such as the common freezing.

Treatment includes painkillers to treat sinus headache, corticosteroid nasal spray and decongestant nasal sprays (which should not be used for more than 3 days). Antibiotics can be used to treat acute sinusitis that is caused by a bacterial infection.

If you own chronic (ongoing) rhinosinusitis and nasal polyps, nasal corticosteroid spray and possibly also a short course of corticosteroid tablets may be recommended.

Nasal polyps can also be removed surgically.

Upper airway cough syndrome

Upper airway cough syndrome is treated with first-generation antihistamines (e.g. chlorpheniramine) and decongestant medicines (such as pseudoephedrine) taken as tablets. A response to treatment helps confirm the diagnosis.

What helpful of allergies cause post nasal drip

Decongestants should only be used for a short time.

Talk to your doctor if you are constantly clearing your throat or own an irritating cough. Finding out the cause of your symptoms and treating the cause should make you feel a lot more comfortable.

Last Reviewed: 04/07/2018



1. Cough (published March 2015; amended March 2018). In: eTG finish. Melbourne: Therapeutic Guidelines Limited; Mar 2018. https://tgldcdp.tg.org.au (accessed Jun 2018).
2. Rhinitis and rhinosinusitis (published March 2015). In: eTG finish. Melbourne: Therapeutic Guidelines Limited; Mar 2018. https://tgldcdp.tg.org.au (accessed Jun 2018).

3. Mayo Clinic. Chronic cough (updated 22 Aug 2017). https://www.mayoclinic.org/diseases-conditions/chronic-cough/symptoms-causes/syc-20351575 (accessed Jun 2018).

What helpful of allergies cause post nasal drip

4. Morcom S, Phillips N, Pastuszek A, Timperley D.

What helpful of allergies cause post nasal drip

Sinusitis. Australian Family Physician 2016;45(6):374-7.

What helpful of allergies cause post nasal drip

https://www.racgp.org.au/afp/2016/june/sinusitis/ (accessed Jun 2018).
5. Mayo Clinic. Nonallergic rhinitis (updated 4 Jan 2018). https://www.mayoclinic.org/diseases-conditions/nonallergic-rhinitis/symptoms-causes/syc-20351229 (accessed Jun 2018).
6. BMJ Best Practice. Upper airway cough syndrome (updated Dec 2016; reviewed May 2018). https://bestpractice.bmj.com/topics/en-us/1209 (accessed Jun 2018).

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How this works.

Causes of post-nasal drip

There are several conditions that can cause post-nasal drip.

Rhinitis (inflammation of lining of the inside of your nose) is one of the most common causes of post-nasal drip. Rhinitis is often due to allergies (allergic rhinitis, also called hay fever) but can be caused by other things such as the common freezing, hormonal changes and certain medicines.

Sinusitis also commonly causes post-nasal drip and/or a runny nose (or blocked nose), as well as facial pain/pressure, cough and a loss of smell.

Acute sinusitis is inflammation of the sinuses (cavities within the facial bones that surround your nose) generally due to a viral or bacterial infection. Chronic rhinosinusitis is when there is ongoing inflammation of the lining of the nose and sinuses, with symptoms lasting longer than 12 weeks. Some people with chronic rhinosinusitis develop nasal polyps – benign (non-cancerous) growths that grow from the lining of the nose or sinuses.

People with upper airway cough syndrome own post-nasal drip, abnormal sensations in the throat plus a chronic (ongoing) cough.

In some people with this condition, extra-sensitive nerves in the back of the throat may cause a feeling of increased mucus in the throat when there is, in fact, no increase in mucus. Allergies and inhaled irritants can trigger upper airway cough syndrome.

Post-nasal drip also can be caused by changes in temperature and humidity, which can affect the quantity or thickness of mucus in the nose and throat. Freezing weather can sometimes increase mucus production, and heating in winter can result in thickened mucus.

Self care for post-nasal drip

Treatments for post-nasal drip generally depend on the cause.

However, there are several things you can do yourself to assist improve the symptoms, no matter what the cause.

  1. Use a saline (salt water) nasal spray. This can assist flush the nose of allergens (substances that you are allergic to) and irritants and also thin mucus. Some people discover that using a neti pot (carefully following the manufacturer’s instructions regarding use and cleaning) is a excellent way to wash out the nose.
  2. Stay well hydrated to assist thin mucus secretions.

    What helpful of allergies cause post nasal drip

    Drink plenty of fluids – water is the best choice for staying well hydrated. A warm drink of tea, broth or warm water with half a teaspoon of honey may assist soothe your throat as well. Avoid anything that tends to dehydrate, such as alcohol and caffeine, as much as possible.

  3. Try to work out what triggers your symptoms and avoid these triggers, if possible.