The fastest way to get phlegm out is a technique called huff coughing, which loosens mucus without collapsing your airways the way a regular forceful cough does. But clearing phlegm effectively usually takes a combination of approaches: the right coughing technique, adequate hydration, humidity control, and sometimes an over-the-counter expectorant. Here’s how each method works and when to use it.
Use the Huff Cough Instead of Regular Coughing
A normal, forceful cough can actually trap mucus by causing your airways to narrow and collapse around it. The huff cough generates just enough force to move phlegm upward without that collapse. Many people describe it as the same motion you’d use to fog up a mirror: smaller, more forceful exhales rather than one big cough.
Here’s the full technique:
- Sit in a chair or on the edge of your bed with both feet on the floor.
- Tilt your chin up slightly and open your mouth.
- Take a slow, deep breath until your lungs are about three-quarters full.
- Hold that breath for two to three seconds. This lets air get behind the mucus and separate it from your lung walls.
- Exhale slowly but forcefully, like you’re fogging a mirror. This is the “huff.” It moves mucus from your smaller airways into your larger ones.
- Repeat one or two more times.
- Finish with one strong, traditional cough to clear the mucus from the larger airways.
This cycle works well first thing in the morning or after a steam shower, when mucus is already loosened. You can repeat it several times throughout the day.
Drink Water to Thin Mucus From the Inside
Staying hydrated doesn’t just help in a vague, general-wellness way. Your airways are lined with a thin liquid layer, and when you’re dehydrated, the blood supplying your airways becomes more concentrated. Your airway tissue responds by pulling water back from that liquid layer, making it thinner and stickier. This can cause small airways to collapse and trap mucus.
Research published in the Journal of Applied Physiology found that drinking water rapidly normalizes the concentration of blood plasma, which in turn restores the airway liquid layer to its hydrated state, reduces surface tension, and reopens collapsed small airways. Interestingly, the same study found that inhaling nebulized saline did not produce the same effect. The mucus layer absorbed the mist like a sponge without actually changing the composition of the deeper airway lining. In other words, drinking water works better than breathing in moisture when it comes to thinning mucus at its source.
There’s no magic number of glasses, but if your urine is dark yellow, you’re likely dehydrated enough for it to affect your airways.
Use Steam and Humidity to Loosen Phlegm
While drinking water works from the inside, warm humid air works from the surface. A hot shower, a bowl of steaming water with a towel over your head, or a room humidifier can all soften thick mucus so it’s easier to cough up.
Indoor humidity below about 30% dries out your nasal passages and airways, making phlegm stickier and harder to clear. The recommended range for respiratory comfort is 30 to 40%, especially during winter months when heating systems pull moisture from the air. A simple hygrometer (available for a few dollars at most hardware stores) can tell you where your home falls.
Be careful not to push humidity above 50%, though. Excess moisture encourages mold and dust mites, which can trigger more mucus production.
Try an Over-the-Counter Expectorant
Guaifenesin is the only OTC expectorant widely available, and it works by thinning mucus so it’s easier to cough out. It won’t stop you from producing phlegm, but it makes what’s there less thick and sticky.
For adults, the standard short-acting dose is 200 to 400 mg every four hours. Extended-release versions are taken as 600 to 1,200 mg every twelve hours. Children aged 6 to 12 take half the adult dose. It should not be given to children under 4 years old.
Guaifenesin works best when you’re also drinking plenty of water. Taking it without adequate fluids limits its effectiveness, since the drug relies on hydration to thin the mucus.
Use Gravity to Drain Your Lungs
Postural drainage uses body positioning to let gravity pull mucus out of different parts of your lungs and into your larger airways, where you can cough it up. It’s especially helpful if you have a lot of congestion deep in your chest.
The basic idea is simple: position yourself so the congested part of your lung is above your airway opening. A few effective positions include sitting upright and leaning forward over your thighs (which drains the front upper lobes), lying on your stomach with a pillow under your hips to create a slight downward angle (which drains the lower lobes), and lying on one side with a pillow under your waist (which drains the opposite lung). Hold each position for five to ten minutes while doing cycles of huff coughing.
If you feel dizzy or short of breath in any position, sit upright and try a different one.
Breathing Devices That Help
Positive expiratory pressure (PEP) devices are handheld tools you breathe into that create resistance when you exhale. This back-pressure forces air behind mucus and holds your airways open so they don’t collapse. A typical session takes about 20 minutes.
Oscillating PEP devices (brands like Flutter and Aerobika) add vibrations to the resistance, which shake mucus loose from airway walls while simultaneously pushing air behind it. These are available without a prescription at most pharmacies and are commonly used by people with conditions like COPD, bronchiectasis, or cystic fibrosis. They can also help during a bad chest cold.
Dairy Does Not Cause More Phlegm
The belief that milk increases mucus production is one of the most persistent health myths around, but it doesn’t hold up. When milk mixes with saliva in your mouth, it creates a briefly thick coating on the throat that can feel like mucus. That sensation is real, but it’s not phlegm, and it doesn’t reach your lungs. Studies going back to 1948, including one that tested children with asthma drinking dairy milk versus soy milk, have found no difference in actual mucus production.
What Phlegm Color Tells You
Clear or white phlegm is typical during colds, allergies, or mild irritation. If you have asthma or COPD and notice more white phlegm than usual, it may mean your condition needs better management.
Yellow or green phlegm usually signals an infection. The color comes from immune cells fighting off bacteria or viruses. Most of these infections clear on their own: bacterial infections typically resolve within 10 to 14 days even without antibiotics, and viral infections can linger up to three weeks depending on the season.
Red, pink, or bloody phlegm is the one color that warrants prompt medical attention. Brown phlegm can be normal for people with chronic lung conditions, but a sudden change in color or amount may signal a flare-up that needs treatment.