What Causes Clear Mucus in the Back of the Throat?

Mucus is a slippery substance that serves as a protective lubricant in certain parts of the body, such as the sinuses and throat. It's produced by mucus cells in mucus glands and contains primarily water, mucin, salts, electrolytes and various types of cells, such as epithelial cells. We have mucus in our throat even when we are healthy, but a build-up of clear or colored mucus in the throat is usually a sign the body is responding to an infection or allergy 1.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


Allergies and hay fever can trigger a buildup of clear mucus that may run through the nasal passages at first 1. However, if there is too much mucus, you may experience post-nasal drip as the mucus runs down the back of your throat. The mucus forms when the lining of the sinus passages become irritated 1. This can occur in response to airborne particles to which you are allergic. Pollutants in the air can also produce clear mucus buildup, so be careful heading outside when air quality is poor, particularly if you are susceptible to sinus and allergy problems 1.

Acute Sinusitis

Acute sinusitis is a condition marked by swollen nasal passages 2. That swelling restricts drainage in your sinuses, which in turn causes mucus to build up, according to MayoClinic.com 2. The cause of acute sinusitis could be a bacterial infection or a fungal infection 2. Sleeping on your back while you have a sinus infection also leads to mucus pooling in the back of the throat, which can lead to a sore throat and trouble sleeping 1.


Yes, along with weight gain, emotional highs and lows and morning sickness, mucus build-up can be a result of pregnancy. The Cleveland Clinic explains that hormonal changes during pregnancy can dry out the lining of your nasal passages, causing them to become inflamed 3. With drainage a problem, mucus can be discharged through the nose or the throat. Clinic doctors recommend placing a warm, wet washcloth across your nose and cheeks to reduce congestion.

Common Cold

The color may change to yellow or green, depending on the nature of the infection. Drinking lot of fluids and resting your body is often the best solution to riding out a cold.