The most effective way to loosen phlegm in your lungs is to combine hydration, specific breathing techniques, and body positioning to thin the mucus and move it upward where you can cough it out. Lung mucus is normally about 97.5% water, and when that balance shifts even slightly, the mucus thickens and becomes much harder for your airways to clear. The good news is that most strategies work quickly, and you can start several of them right now at home.
Why Phlegm Gets Stuck
Your airways are lined with tiny hair-like structures called cilia that sweep mucus upward and out of your lungs in a continuous conveyor-belt motion. This system works well when mucus has its normal composition of roughly 1.5% organic solids and 97.5% water. But when mucus dries out or thickens to around 4 to 6% solids, it becomes stiff enough to resist the cilia’s sweeping motion. At 8 to 10% solids, the thick mucus can actually flatten the cilia entirely, shutting down clearance altogether.
This thickening happens during infections, dehydration, dry indoor air, or chronic lung conditions. Your body has a built-in feedback loop: when cilia strain against thick mucus, the cells release signaling molecules that trigger fluid secretion to rehydrate the mucus layer. But during illness or in very dry environments, this system can’t keep up on its own. That’s where the strategies below come in.
Stay Hydrated to Thin Mucus From the Inside
Drinking enough fluids is the simplest and most important step. The fluid that hydrates your lung mucus comes from your airway lining cells, which pull water from your bloodstream. When you’re well-hydrated, those cells can secrete enough fluid to keep mucus at its ideal consistency. When you’re dehydrated, they can’t.
Water, broth, herbal tea, and warm liquids all count. Warm fluids have a slight edge because the warmth and steam can help loosen mucus on contact in the throat and upper airways. There’s no magic number of glasses per day, but if your urine is pale yellow, you’re likely drinking enough. If you’re sick with a fever or breathing through your mouth at night, you’ll need more than usual because both increase fluid loss.
Use Breathing Techniques That Move Mucus Up
Regular coughing is the body’s default mucus-clearing tool, but when phlegm is deep in the lungs, a standard cough often isn’t enough. A technique called huff coughing is significantly more effective at moving mucus from the smaller airways into the larger ones where it can be expelled.
Think of it as the same action you’d use to fog up a mirror. Instead of one big, forceful cough, you take a normal breath in and then exhale in short, sharp bursts with your mouth open, using your stomach muscles to push air out. Repeat this one or two more times, then follow with a single strong cough to clear the mucus from the larger airways. Do two or three rounds depending on how congested you feel.
One important detail: avoid breathing in quickly and deeply through your mouth right after coughing. Rapid inhalation can pull loosened mucus back down into smaller airways and trigger uncontrolled coughing fits. Instead, breathe in slowly and gently through your nose between rounds.
Position Your Body to Let Gravity Help
Postural drainage uses gravity to pull mucus out of different parts of your lungs. The idea is simple: position your body so the congested area of your lungs is above your airways, and gravity does some of the work for you.
Different positions target different lung segments. Lying on your stomach with a pillow under your hips drains the lower back portions of your lungs. Lying on each side drains the corresponding side. Lying on your back with your hips elevated on pillows helps drain the lower front portions. Sitting upright and leaning slightly forward works for the upper lobes. Stay in each position for five to ten minutes while doing slow, deep breathing or huff coughing.
Combining postural drainage with gentle percussion (having someone cup their hands and rhythmically pat your back and chest over the congested area) can shake mucus loose from airway walls. The vibration helps dislodge sticky phlegm so gravity and coughing can finish the job.
Adjust Your Indoor Humidity
Dry air pulls moisture from your airway lining and thickens mucus. This is especially common in winter when heating systems strip humidity from indoor air. The Mayo Clinic recommends keeping indoor humidity between 30% and 50%. A simple hygrometer (available for a few dollars at hardware stores) can tell you where you stand.
A cool-mist humidifier in your bedroom is the most practical fix. If you don’t have one, spending 10 to 15 minutes in a steamy bathroom (run the hot shower with the door closed) can provide temporary relief. Just clean humidifiers regularly, because mold and bacteria growing in a dirty water tank will make congestion worse, not better.
Over-the-Counter Expectorants
Guaifenesin is the main over-the-counter expectorant available in most pharmacies. It works by thinning and loosening mucus in your airways, making it easier to cough up. You’ll find it as the active ingredient in products like Mucinex and Robitussin. Follow the dosing instructions on the package, and use the measuring device that comes with liquid formulations rather than a household spoon, which is often inaccurate.
Guaifenesin works best when paired with adequate fluid intake. Taking it without drinking enough water limits its effectiveness because the medication relies on available fluid to thin the mucus.
Honey as a Natural Option
Honey has solid evidence behind it for respiratory symptom relief. A systematic review combining data from multiple clinical trials found that honey reduced cough frequency and cough severity compared to standard over-the-counter treatments. Its thick, viscous texture coats and soothes irritated mucous membranes, and it has mild antibacterial and anti-inflammatory properties that may help with the underlying irritation driving mucus production.
A spoonful of honey on its own or stirred into warm water or tea is the simplest way to use it. It’s safe for adults and children over one year old but should never be given to infants under 12 months due to botulism risk.
Devices That Loosen Mucus Mechanically
Positive expiratory pressure (PEP) devices are handheld tools you breathe through. Air flows in freely when you inhale, but when you exhale, the device creates resistance that forces you to breathe out harder. This back-pressure pushes air behind and underneath mucus stuck to airway walls, prying it loose. It also holds your airways open, preventing them from collapsing during exhalation.
Oscillating PEP devices (like the Acapella or Flutter valve) add vibrations to the exhaled air, which further shake mucus free from airway surfaces. These devices are commonly used by people with chronic conditions like cystic fibrosis or bronchiectasis, but they can help anyone dealing with persistent, hard-to-clear congestion. Most are available without a prescription, though getting guidance on proper technique from a respiratory therapist makes them more effective.
Nebulized Saline for Stubborn Congestion
For thick mucus that doesn’t respond to simpler measures, nebulized hypertonic saline (a concentrated saltwater solution, typically 3% to 7%) can be inhaled as a fine mist. The high salt concentration draws water into your airways through osmosis, rapidly rehydrating dried-out mucus and making it much easier to cough up. Standard saline (0.9%) also helps, though the hypertonic versions are more effective for truly stubborn phlegm.
Hypertonic saline typically requires a prescription and a nebulizer. It can cause throat irritation or trigger coughing in some people, which is actually part of how it works, since that coughing helps move the newly loosened mucus out.
What Phlegm Color Tells You
Clear or white phlegm is typical of viral infections, allergies, or mild irritation. Yellow or green phlegm indicates your immune system is actively fighting an infection, with the color coming from enzymes in white blood cells. This alone doesn’t mean you need antibiotics. Bacterial respiratory infections often resolve on their own within 10 to 14 days, while viral infections can cause lingering mucus for up to three weeks.
Red, pink, or bloody phlegm is the color that warrants prompt medical attention. This is especially important if you smoke. Brown, sticky phlegm in someone with a chronic lung condition like cystic fibrosis or bronchiectasis can signal a flare-up that may need more aggressive treatment, including antibiotics.