Drinking more water is the single most effective thing you can do to thin out phlegm and make it easier to clear. In one study of people with chronic postnasal drip, hydration reduced the thickness of nasal secretions by roughly 70%, and 85% of participants reported noticeable symptom relief. Beyond fluids, a combination of breathing techniques, over-the-counter medications, and simple environmental changes can help you move phlegm out faster.
Why Staying Hydrated Makes the Biggest Difference
Phlegm thickens when your body is low on fluids. Water, broth, and warm teas all help thin the mucus lining your airways, making it easier to cough up or drain naturally. The effect is measurable: research published in the journal Rhinology found that people who were dehydrated had mucus roughly four times thicker than when they were well-hydrated. After drinking fluids, not a single participant felt worse, and the vast majority noticed improvement.
Warm liquids have an added advantage. Hot tea, soup, or even plain warm water can soothe irritated airways and temporarily increase the speed at which tiny hair-like structures in your nose and throat sweep mucus along. There’s no magic number of glasses per day, but if your phlegm feels sticky or hard to clear, you’re likely not drinking enough.
Over-the-Counter Medications That Work
Two types of medication target phlegm directly, and they work differently. Expectorants (the active ingredient is guaifenesin, sold as Mucinex or Robitussin) thin mucus and make your coughs more productive. For adults, the typical dose is 2 to 4 teaspoons of the liquid form every four hours, with a maximum of six doses in 24 hours. Guaifenesin won’t stop you from coughing. That’s the point: it helps each cough actually move phlegm out.
Mucolytics take a different approach. They break apart the molecular bonds that hold mucus together, making it less gel-like and easier to clear from your lungs. Your doctor may recommend a prescription mucolytic if you have a chronic condition like COPD or cystic fibrosis that causes persistent, thick mucus. For a standard cold or sinus infection, guaifenesin is usually sufficient.
The Huff Cough Technique
Regular coughing can be exhausting and sometimes pushes mucus back down rather than up. The huff cough is a controlled breathing technique that moves phlegm through your airways more efficiently. Think of it as fogging up a mirror rather than barking out a full cough.
Sit upright with both feet on the floor. Tilt your chin slightly up and open your mouth. Breathe in slowly until your lungs are about three-quarters full, then hold for two to three seconds. This gets air behind the mucus. Exhale slowly but forcefully, like you’re trying to fog a window. Repeat this one or two more times, then follow with a single strong cough to push the loosened mucus out. You can do the full sequence two or three times depending on how congested you feel.
One important detail: avoid gasping in quickly through your mouth between huffs. Quick inhales can pull mucus back down into the smaller airways and trigger uncontrolled coughing fits.
Saline Rinses for Sinus and Throat Phlegm
If your phlegm is concentrated in your sinuses or dripping down the back of your throat, a saline nasal rinse (using a neti pot or squeeze bottle) can flush it out directly. Saline irrigation works through several mechanisms at once: it physically washes away mucus, removes inflammatory compounds that trigger more mucus production, and increases the beat frequency of the cilia that move mucus along naturally.
A study of woodworkers exposed to heavy dust found that daily saline irrigation significantly improved both sinus symptoms and mucociliary clearance. Research on people with viral upper respiratory infections showed that even a simple saline spray improved nasal airflow and reduced symptom severity. Use distilled or previously boiled water (never tap water) with a pre-made saline packet, and rinse once or twice daily when congested.
Honey as a Natural Option
Honey won’t thin mucus directly, but it can reduce the coughing that often accompanies phlegm buildup. Clinical trials have found that honey performs about as well as diphenhydramine, a common ingredient in over-the-counter cough medicines. A spoonful of honey before bed, or stirred into warm tea, coats the throat and may calm the irritation that triggers repeated coughing. Keep in mind that honey should never be given to children under one year old due to the risk of botulism.
Adjust Your Sleeping Position
Phlegm tends to pool at the back of the throat when you lie flat, which is why congestion often feels worst at night. Elevating your head helps gravity drain mucus away from your throat and sinuses. You don’t need to sleep sitting up. Propping yourself on an extra pillow or sliding a wedge under the head of your mattress is enough to keep things moving. This position also reduces acid reflux, which can itself trigger excess mucus production in the throat.
Keep Indoor Humidity Between 30% and 50%
Air that’s too dry thickens mucus and irritates your airways, prompting your body to produce even more phlegm. Air that’s too humid encourages mold and dust mites, which can trigger allergic mucus production. The sweet spot is 30% to 50% humidity. A cool-mist humidifier in your bedroom during winter months, or in dry climates year-round, can make a noticeable difference. Clean the humidifier regularly to prevent it from spraying bacteria or mold spores into the air.
Steam and Warm Compresses
Breathing in steam from a hot shower, a bowl of hot water, or a facial steamer temporarily loosens mucus in both your sinuses and chest. The moist heat softens thick phlegm and makes it easier to blow your nose or cough productively. A warm, damp washcloth draped over your nose and cheeks can also relieve sinus pressure and encourage drainage. These methods offer short-term relief, usually 15 to 30 minutes, but they’re easy to repeat throughout the day.
What Phlegm Color Actually Means
Many people assume that green or yellow phlegm means a bacterial infection that needs antibiotics. This is a widespread myth, even among some healthcare providers. Both viral and bacterial infections cause the same color changes in mucus. The greenish tint comes from enzymes released by your white blood cells as they fight the infection, regardless of whether the invader is a virus or bacteria. Since viruses cause the vast majority of upper respiratory infections, green phlegm alone is not a reason to take antibiotics.
Clear or white phlegm is typical during allergies or the early stages of a cold. Yellow or green phlegm usually means your immune system is actively fighting something. Pink or rust-colored phlegm can indicate blood, which warrants medical attention if it persists. Phlegm that lasts longer than 10 days, or that comes with a high fever, chest pain, or difficulty breathing, is worth getting checked out.
Milk Does Not Increase Phlegm
The belief that dairy causes more mucus is one of the most persistent health myths around, and research has consistently shown it isn’t true. A study of about 600 people found no difference in mucus production between milk drinkers and non-milk drinkers. When milk mixes with saliva, it briefly creates a thick coating in your mouth and throat that can feel like mucus, but it isn’t. A study in children with asthma found no difference in respiratory symptoms between those drinking dairy milk and those drinking soy milk. You don’t need to avoid dairy when you’re congested.