What Is Postnasal Drip?

Medically Reviewed by Nayana Ambardekar, MD on January 29, 2023
7 min read

Postnasal drip is the accumulation of mucus in the back of the throat, which can cause a feeling of congestion, a sore throat, or a cough. It is a common symptom of conditions such as the common cold, sinusitis, and allergies. The excess mucus can be caused by inflammation or swelling of the nasal passages, which can be due to a variety of factors such as viral or bacterial infections, allergies, or irritants in the air.

Every day, glands in the linings of your nose, throat, airways, stomach, and intestinal tract produce mucus. Your nose alone makes about a quart of it each day. Mucus is a thick, wet substance that moistens these areas and helps trap and destroy foreign invaders like bacteria and viruses before they cause infection.

Normally, you don't notice the mucus from your nose because it mixes with saliva, drips harmlessly down the back of your throat, and you swallow it.

When your body produces more mucus than usual or it’s thicker than normal, it becomes more noticeable.

The excess can come out of the nostrils -- that’s a runny nose. When the mucus runs down the back of your nose to your throat, it's called postnasal drip.

Yellow mucus

Yellow mucus can indicate a bacterial infection in the nasal passages. This type of infection often requires antibiotics to clear up. If the yellow color is accompanied by thick and discolored nasal discharge, it may be a sign of a sinus infection.

Green mucus

Green mucus can be a sign of a more severe viral or bacterial infection. The green color is caused by the presence of white blood cells that are fighting the infection. If the green mucus is accompanied by other symptoms such as fever, it is important to see a doctor for treatment.

Clear mucus

Clear mucus is normal and indicates that the nasal passages are healthy. It is the body's way of trapping dust, dirt, and other particles from entering the lungs. Clear mucus is also seen in the beginning stages of a cold or allergy and is often the sign that the body is fighting off an infection or irritation.

White mucus

White mucus is also normal, and can be a sign that the body is producing a thicker mucus in response to an irritation or infection. It can also be caused by dry air or exposure to irritants such as smoke or pollution.

Brown mucus

Brown mucus can be a sign of exposure to pollution or smoking. It can also be caused by the presence of dried blood, which can occur from blowing the nose too hard. If the brown color is accompanied by other symptoms, it is important to see a doctor to rule out any serious conditions.

Black mucus

Black mucus is not a common color and can be a sign of exposure to very high levels of pollution or smoke. It can also indicate a fungal infection. If the black color is accompanied by other symptoms, it is important to see a doctor for treatment.

Red mucus

Red mucus can be a sign of bleeding in the nasal passages. This can occur from blowing the nose too hard or from a more serious condition such as cancer. If the red color is accompanied by other symptoms, it is important to see a doctor for treatment.

The excess mucus that triggers it has many possible causes, including:

  • Flu
  • Allergies, also called allergic postnasal drip
  • Sinus infection or sinusitis, which is an inflammation of the sinuses
  • Object stuck in the nose (most common in children)
  • Certain medications, including some for birth control and blood pressure
  • Deviated septum, which is the crooked placement of the wall that separates the two nostrils, or some other problem with the structure of the nose that affects the sinuses
  • Changing weather, cold temperatures, or really dry air
  • Certain foods (for example, spicy foods may trigger mucus flow)
  • Fumes from chemicals, perfumes, cleaning products, smoke, or other irritants

Sometimes the problem is not that you're producing too much mucus, but that it's not being cleared away. Swallowing problems can cause a buildup of liquids in the throat, which can feel like postnasal drip. These problems can sometimes occur because of a blockage or conditions such as gastroesophageal reflux disease, also known as GERD.

Postnasal drip makes you feel like you constantly want to clear your throat.

It also can trigger a cough, which often gets worse at night. In fact, postnasal drip is one of the most common causes of a cough that just won’t go away.

Too much mucus may also make you feel hoarse and give you a sore, scratchy throat.

If the mucus plugs up your Eustachian tube, which connects your throat to your middle ear, you could get a painful ear infection.

You could also get a sinus infection if those passages are clogged.

Postnasal drip and nausea

Nausea is not a typical symptom of postnasal drip, but it can be associated with it in some cases. When mucus accumulates in the throat, it can cause a feeling of congestion and discomfort, which may lead to nausea.

Additionally, some people may experience nausea when taking certain medications used to treat postnasal drip symptoms such as decongestants. These medications can cause stomach upset and may lead to nausea in some individuals. If you are experiencing nausea while taking these medications, it is important to speak with your doctor about alternative treatment options.

How you treat postnasal drip depends on what’s causing it. Antibiotics can clear up a bacterial infection. However, green or yellow mucus is not proof of a bacterial infection.

Colds can also turn the mucus these colors, and they are caused by viruses, which don't respond to antibiotics.

Antihistamines and decongestants can often help with postnasal drip caused by sinusitis and viral infections. They can also be effective, along with steroid nasal sprays, for postnasal drip caused by allergies.

The older, over-the-counter antihistamines, including diphenhydramine (Benadryl) and chlorpheniramine (Chlor-Trimeton), might not be the best choices for postnasal drip. When they dry out mucus, they can actually thicken it.

Newer antihistamines like cetirizine (Zyrtec), desloratadine (Clarinex), fexofenadine (Allegra), levocetirizine (Xyzal), and loratadine (ClaritinAlavert), may be better options and are less likely to cause drowsiness. It's a good idea to check with your doctor before taking these because all of them can have side effects that range from dizziness to dry mouth.

Another option is to thin your mucus. Thick mucus is stickier and more likely to bother you. Keeping it thin helps prevent blockages in the ears and sinuses. A simple way to thin it out is to drink more water.

Other methods you can try include:

  • Take a medication such as guaifenesin (Mucinex).
  • Use saline nasal sprays or irrigation, like a neti pot, to flush mucus, bacteria, allergens, and other irritating things out of the sinuses.
  • Turn on a vaporizer or humidifier to increase the moisture in the air.

For centuries, people have treated postnasal drip with all kinds of home remedies. Probably the best known and most loved is hot chicken soup.

While it won’t cure you, hot soup or any hot liquid might give you some temporary relief and comfort. It works because the steam from the hot liquid opens up your stuffy nose and throat. It also thins out mucus. And because it’s a fluid, the hot soup will help prevent dehydration, which will make you feel better, too.

A hot, steamy shower might help for the same reason.

You can also try propping up your pillows at night so that the mucus doesn't pool or collect in the back of your throat. If you have allergies, here are some other ways to reduce your triggers:

  • Cover your mattresses and pillowcases with dust mite-proof covers.
  • Wash all sheets, pillowcases, and mattress covers often in hot water.
  • Use special HEPA air filters in your home. These can remove very fine particles from the air.
  • Dust and vacuum regularly.

Call your doctor if the drainage is bad smelling, you have a fever, you're wheezing, or your symptoms are severe or last for 10 days or more. You might have a bacterial infection.

Let your doctor know right away if you notice blood in your postnasal drip. If medication doesn’t relieve your symptoms, you might need to see an ear, nose, and throat specialist (also called an otolaryngologist) for evaluation. Your doctor might want you to get a CT scan, X-rays, or other tests.