Warm liquids are the single most effective thing you can drink to loosen and clear phlegm. Hot water, brothy soups, and herbal teas all work by hydrating the mucus layer in your airways, making it thinner and easier for the tiny hair-like structures in your lungs and throat to push it out. But not all drinks are equal, and temperature matters more than you might expect.
Why Warm Fluids Work Better Than Cold
Your airways are lined with microscopic hair-like structures called cilia that sweep mucus upward and out of your lungs. When mucus is well-hydrated, cilia can propel it efficiently. When it dries out or thickens, the system stalls, and phlegm accumulates. Drinking fluids restores that hydration and gets the clearing mechanism moving again.
Temperature makes a measurable difference. In a study comparing hot and cold beverages, sipping hot water increased the speed at which nasal mucus moved from 6.2 to 8.4 millimeters per minute. Hot chicken soup did even better, pushing it from 6.9 to 9.2 mm per minute. Cold water, on the other hand, actually slowed mucus movement from 7.3 down to 4.5 mm per minute. The effect of warm drinks lasted about 30 minutes, driven partly by inhaling steam while sipping. So drink warm, drink often, and take your time with each cup rather than gulping it down through a straw (the study found straw-sipping produced weaker results because less vapor reaches your nose).
The Best Drinks for Clearing Phlegm
Warm Water With Honey
This is one of the simplest and best-supported options. Honey coats the throat, calms the cough reflex, and helps you tolerate the irritation that phlegm causes. A study published in JAMA Pediatrics found that honey performed as well as dextromethorphan (the active ingredient in many over-the-counter cough syrups) for reducing cough frequency and improving sleep. Parents in the study rated honey the most effective option overall. Stir one to two teaspoons into a mug of warm water or tea. Note: honey should not be given to children under one year old.
Ginger Tea
Ginger does more than just warm your throat. Active compounds in ginger directly relax the smooth muscle tissue that lines your airways. Research published in the American Journal of Respiratory Cell and Molecular Biology showed that several ginger compounds caused rapid relaxation of human airway tissue, with some achieving complete relaxation within 30 minutes. This means ginger tea can help open up tight, phlegm-clogged airways and make coughing more productive. Slice a thumb-sized piece of fresh ginger, steep it in hot water for 10 minutes, and add honey if you like.
Thyme Tea
Thyme has a long history as a respiratory remedy, and clinical evidence backs it up. In a double-blind trial of 361 patients with acute bronchitis and productive cough, a thyme-based preparation reduced coughing fits by 68.7% over about a week, compared to 47.6% with placebo. Patients taking thyme reached a 50% reduction in coughing two full days earlier. You can make thyme tea by steeping one to two teaspoons of dried thyme leaves in boiling water for five to ten minutes. It has a mild, slightly earthy flavor that pairs well with honey and lemon.
Warm Broth and Chicken Soup
Chicken soup isn’t just comfort food. The study on nasal mucus velocity found it outperformed plain hot water, likely because the combination of steam, salt, and warm liquid works on multiple fronts at once. The salt content helps draw water toward the mucus layer, while the steam and warmth boost circulation in the nasal passages. Any warm, clear broth will give you similar benefits.
Warm Saltwater Gargle
While not technically a drink (you spit it out), saltwater gargling is worth mentioning because it directly targets phlegm in the throat. The salt creates a mildly hypertonic solution that pulls water into the mucus through osmosis, thinning it so you can clear it more easily. It also supports the mucosal lining and helps with mucociliary clearance. The CDC recommends mixing one teaspoon of salt into a cup of warm water. Gargle for 15 to 30 seconds and repeat a few times a day.
Peppermint Tea: Helpful but Not What You Think
Peppermint tea feels like it opens up your airways, and that sensation is real, but it’s mostly an illusion. Menthol, the active compound in peppermint, triggers cold receptors in your nose and throat, creating a powerful feeling of improved airflow. However, studies using objective measurements found that menthol inhalation does not actually change airway resistance or ventilation. It won’t thin your phlegm or speed up mucus clearance. That said, the subjective relief is genuine comfort when you’re congested, and the warm liquid itself still helps. Just don’t rely on peppermint alone if your goal is to actually move phlegm out.
Marshmallow Root Tea for Throat Irritation
If constant coughing and throat-clearing has left your throat raw, marshmallow root tea can help. The plant produces a thick, gel-like substance called mucilage that coats the inner lining of your throat and esophagus, forming a protective barrier. This won’t break up phlegm directly, but it soothes the irritation that makes you cough more, which can become a vicious cycle. You can find marshmallow root tea bags at most health food stores. Steep it longer than regular tea (10 to 15 minutes) to extract more of the mucilage.
Milk Does Not Make Phlegm Worse
You’ve probably heard that dairy increases mucus production. It doesn’t. The Mayo Clinic states clearly that drinking milk does not cause the body to make more phlegm. What happens is that milk and saliva mix to form a slightly thick coating in the mouth and throat, and that sensation gets mistaken for extra mucus. Studies have tested this directly: people who drank milk produced no more mucus than those who didn’t. Even in children with asthma, who are commonly told to avoid dairy when congested, researchers found no difference in symptoms between dairy milk and soy milk. If warm milk or a latte sounds appealing when you’re sick, it won’t set you back.
How Long It Takes to Feel Better
If your phlegm is from a typical cold or upper respiratory infection, symptoms usually peak between days three and five, then gradually improve. Most infections resolve within 10 to 14 days even without treatment. Staying well-hydrated with warm fluids throughout the day can make those days more comfortable and help your body clear the mucus faster, but it won’t dramatically shorten the timeline. Aim for warm drinks every one to two hours when symptoms are at their worst.
Keep an eye on the color and duration of your phlegm. Clear or white mucus is typical during a cold. If your phlegm turns bright yellow, green, or especially dark, or if you notice blood in it, those are signs your body may be fighting a more serious infection. Persistent phlegm lasting well beyond two weeks, or phlegm accompanied by facial pain, headaches, fever, or shortness of breath, warrants a visit to a healthcare provider to check for a bacterial infection or another condition that drinks alone won’t resolve.