Phlegm in Throat: 11 Causes & What to Do

Updated in October 2022

Phlegm in the throat can emerge due to decreased water intake throughout the day or from being in dry environments or rooms. These conditions can lead to dryness and irritation in the throat and can make phlegm thicker, although this sensation can be relieved by ensuring adequate hydration and fluid intake throughout the day. 

A phlegmy throat can also occur with respiratory inflammation or infections, like tonsillitis, pharyngitis, or sinusitis, or even with GERD. It can be accompanied by other symptoms, like a sore throat, coughing, fever, and yellow or green phlegm. 

If you notice persistent phlegm in the throat, especially if it worsens quickly or appears with other symptoms, you should consult a doctor for assessment. Depending on the underlying cause, treatment can be initiated with analgesics, anti-inflammatories and/or antibiotics.

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The main causes of phlegm in the throat are: 

1. Not drinking enough water

Drinking insufficient amounts of water during the day can lead to a dry throat and make the phlegm thicker. Water makes up a great deal of phlegm composition, and decreased water content can contribute to the sensation of phlegm stuck in the throat. 

What to do: Ideally, you should keep the throat hydrated by drinking at least 2 L of water per day in small sips. This helps to thin out the phlegm and relieves the sensation that it is stuck in the throat. If you have difficulty drinking enough water, you can add lemon juice to add flavor. 

2. Dry air or air conditioning

Dry air can lead to a dry nose and throat, causing irritation and thick phlegm. Decreased humidity in the air can cause symptoms like the feeling that phlegm is constantly stuck in the throat, dry cough, post-nasal drip and even hoarseness. 

Air conditioning can also try out the air, which can cause throat irritation and constant phlegm. 

What to do: You should avoid air conditioning and dry environments when possible. Be sure to drink plenty of water and to hydrate the nose or throat if needed (with nasal spray for example). You can also use a humidifier to increase the moisture in the air, reduce throat irritation and inflammation, and to open the airways, which will promote phlegm release.  

3. Sinusitis

Sinusitis is an inflammation of the nasal cavities, which are found around the nose and eyes. It is caused by allergies, as well as viral, fungal or bacterial infections, and results in the accumulation of phlegm in the throat. 

Excess phlegm can lead to post-nasal drip as well as coughing, swelling, throat irritation, a scratchy throat and green or yellow phlegm.

What to do: Treatment for sinusitis usually involves medications prescribed by a doctor, like analgesics, anti-inflammatories, nasal decongestants and antibiotics. To complement prescribed treatment, you can also perform nasal irrigations with salt water or saline solution. You can also inhale water vapor to thin out the phlegm. 

4. Cold and flu

The cold and flu are viral infections that affect the nose and throat. They are associated with symptoms like throat inflammation or irritation, white or gray phlegm, sore throat, coughing, fever, sneezing, headaches and body aches. Learn more about how to tell the difference between a cold and flu

What to do: You should ensure you are getting plenty of rest and fluids to guarantee a quick recovery. The doctor may recommend analgesics, anti-inflammatories, or decongestants (like acetaminophen, ibuprofen and loratadine, for example) to relieve associated symptoms. Read more about home remedies for the cold and flu that you can use to relieve symptoms naturally. 

5. Tonsillitis 

The presence of phlegm in the throat can also be caused by a tonsil infection from Streptococcus pyogenes bacteria.

Other symptoms of strep throat include phlegm with pus, intense throat pain, difficulty swallowing, and high grade fever. 

What to do: The treatment for strep throat should be guided by a doctor, who may prescribe antibiotics like amoxicillin, azithromycin, clindamycin or cephalosporin. 

6. Allergic rhinitis

Allergic rhinitis is an inflammation of the nasal muscosa that can lead to accumulation of phlegm in the throat. This phlegm can drip into the throat, causing a constant sensation of phlegm in the throat, as well as a stuffy or runny nose, tearing eyes and sneezing. 

Allergic rhinitis is caused by coming into contact with allergens, like dust, pollen, fur, and some plants. It is especially felt during the spring and fall seasons. 

What to do: Treatment for allergic rhinitis should be guided by an allergy and will depend on the intensity and frequency of symptoms. Treatment can involve the use of allergy medication, like loratadine or cetirizine. You should also avoid the trigger when possible. 

7. Pharyngitis

Pharyngitis is an inflammation of the pharynx, which is located at the back of the throat. It can be caused by a viral infection, like adenovirus, rhinovirus or influenza, or a bacterial infection, like Streptococcus pyogenes. This condition is associated with symptoms like throat pain, difficulty swallowing, a scratchy or itchy throat, and green or yellow phlegm. 

Some people may also experience fever, headache, general malaise and hoarseness. 

What to do: Treatment for pharyngitis varies depending on the symptoms and underlying cause. The doctor may prescribe analgesics, anti-inflammatories or antibiotics. Plenty of rest and fluid is also very important for a quick recovery. 


Gastroesophageal reflux disorder (GERD) is the backflow of stomach content into the esophagus and mouth. This backflow of acid can irritate the tissues can cause pain, a bad taste in the mouth, an itchy throat and the sensation of phlegm in the throat. Learn more about what causes GERD and the other symptoms associated with it. 

What to do: Treatment for GERD should be monitored by a gastroenterologist and can involve the use of antacids, stomach protectors, and medications that speed up stomach emptying to prevent the backflow of acid up toward the mouth. Check out some natural remedies for acid reflux that you can use to complement your medical treatment. 

9. Exposure to irritating substances 

Exposure to irritating substances, like cigarette smoke and pollution, can irritate the throat and cause chronic inflammation. This can lead to an increase production and accumulation of phlegm in the throat. 

Other symptoms can include a scratchy throat, itchiness and sore throat. 

What to do: Avoiding exposure to substances that can cause throat irritation is the most effect measure you can take. If avoiding the trigger is not possible, you can chew on soothing lozenges that contain honey, lemon or ginger. Gargling with salt water solutions can also help relieve symptoms.

If you are a smoke, you are advised to see your doctor for smoking cessation strategies and medications, like bupropion or varenicline. 

10. Lung problems

Some lung problems, like bronchitis, asthma or pneumonia, can increase mucus production in the lungs, and also cause nasal congestion and coughing up clear, yellow, gray or bloody phlegm. 

These respiratory problems can also cause throat pain or irritation, phlegm in the throat, difficulty breathing, wheezing, fever and fatigue.

What to do: You should see a doctor to start appropriate treatment for the lung problem diagnosed. He or she may prescribe medications like corticosteroids or bronchodilating puffers, analgesics, anti-inflammatories, expectorant cough syrup, mucolytics or antibiotics. 

11. Using nasal decongestants

Nasal decongestants, like nasal sprays that contain naphazoline and pseudoephedrine, cause constriction of the blood vessels in the nose. This helps to manage increased production of mucus in the nose, which can drip into the throat. 

However, using decongestants excessively or for prolonged periods of time can lead to a rebound effect, in which the blood vessels in the nose actually dilate in response to decreased blood flow in the nose. This can lead to worsening of congestion symptoms.

What to do: You should only use nasal decongestants as recommended by your doctor for the least amount of time possible. 3 to 7 days is usually sufficient in treating a condition, depending on the active ingredient in the decongestant.