7 Phlegm-Causing Foods You Want to Limit, According to a Pulmonologist and Gastro RD

Learn about foods that cause phlegm in the throat. Plus, get tips and tricks on how to get rid of phlegm and keep those incessant mucus-clearing coughs at bay.

What is phlegm?

“Phlegm, aka sputum, is a mixture of saliva from the mouth and mucus produced by the lungs,” explains Amarbir Mattewal, MD, a pulmonologist with Memorial Hermann The Woodlands Medical Center. “It contains cells, microorganisms, proteins, and other particles.”

While phlegm isn’t exactly pleasant, it serves a few important purposes. Per Dr. Mattewal, its functions include but aren’t limited to:

• Helping to lubricate and protect the respiratory tract from irritation and injury
• Trapping and removing dust, microorganisms (e.g., bacteria, viruses, and fungi), and other irritants from the respiratory tract

Any number of things can trigger excess phlegm production—including but not limited to lung disease, acid reflux or GERD, and environmental triggers, such as dust, smoke, and air pollution. However, certain foods can also cause phlegm after eating them.

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7 foods and drinks that cause phlegm

1. Foods high in sugar

When you indulge your sweet tooth, there’s a chance you’ll be left with more than just a sugar rush. High-sugar foods and drinks (think: candy, baked foods, and soda) are some of the top items that cause phlegm since they increase blood glucose levels, says Adrian Hernandez, RDN, a certified gastrointestinal dietitian nutritionist and owner of AEH Nutrition LLC, an insurance-based practice in the Washington, DC area. “This can suppress the immune system and cause inflammation, increasing mucus production,” he explains.

2. Fried and fatty foods

As is the case with sugary foods, you’re better off limiting your consumption of fried and fatty foods—both for the sake of reducing phlegm and minding your greater health. Tasty as they may be, the likes of fried chicken, pizza, and ooey-gooey cheeseburgers are among the top foods that promote mucus. They can trigger inflammation and are hard to digest, says Hernandez, “producing mucus as the body tries to protect the digestive tract and increase motility.”

3. Spicy foods

We hate to be the bearer of bad news, but if you’re a fan of the hot stuff, spicy foods top the list of things that can cause phlegm in the throat after eating. “Spicy foods can cause the body to produce more mucus as a protective mechanism against the irritation they cause in the mouth and throat,” Hernandez explains. (While I’m more privy to their sweat-inducing effects, those who have GI or respiratory issues may want to take extra caution to limit spicy fare in their diets.)

4. Processed meat

The deli meats you pack onto your weekday lunches, as well as hot dogs and sausages, are a few other common foods that cause phlegm. According to Hernandez, that’s because they contain preservatives and salt, additives that can lead to dehydration and thus, thicken mucus.

5. Caffeinated drinks

Caffeine—including that in coffee, black and green tea, energy drinks, and even chocolate—is a diuretic and can heighten your risk of dehydration. “Dehydration causes mucus to become thicker and more noticeable,” Hernandez says. He also warns that caffeine may trigger GERD and acid reflux, which in turn can increase phlegm production.

6. Alcohol

Alcohol can leave you with excess phlegm in your throat (not to mention a gnarly hangover the next day). Similar to caffeine, alcohol is dehydrating and thus results in thicker mucus. It’s “often a trigger for GERD and acid reflux, irritating the mucosal lining of the throat and increasing mucus production,” Hernandez adds.

6. Dairy products (maybe)

Many people hold off on having milk, cheese, ice cream, and other dairy products when they’re sick. But it’s not necessarily the case that these foods cause phlegm. Rather, what’s happening is that dairy products contain proteins that can temporarily thicken saliva, Hernandez says. Then, when you feel this thick coating in your mouth, it’s natural to think it’s phlegm, per the Mayo Clinic.

What foods reduce phlegm?

Just as these are foods that cause phlegm, there are some that can help keep phlegm at bay. Here, Hernandez details foods and drinks that reduce phlegm:

• Water, as adequate hydration helps keep mucus production within normal bounds
• Warm liquids, which can help loosen and thin mucus, thus making it easier to remove from the body
• Pineapple, courtesy of the enzyme bromelain, which aids digestion and can help thin mucus and reduce inflammation
• Citrus fruits, which are high in vitamin C and thereby boost immune function and help reduce phlegm
• Ginger, which has anti-inflammatory properties and can soothe the respiratory tract as well as GERD
• Honey, which is antimicrobial and anti-inflammatory, and can help soothe the throat and get rid of mucus
• Peppermint, courtesy of cooling menthol, which suppresses coughs and soothes the throat and respiratory tract

Other ways to reduce phlegm

It may be in your best interest to limit foods that cause phlegm, especially if it’s excessive and hinders your quality of life. However, there are other dietary and lifestyle modifications you can make to get rid of phlegm.

On the dietary front, Dr. Mattewal suggests leveling up your hydration game. “Drinking plenty of water helps keep mucus thin and easy to expel,” he explains. He also encourages eating plenty of antioxidant-rich fruits and veggies, which can help reduce inflammation and thereby keep phlegm in check. (An older study² of nearly 50,000 middle-aged adults in Singapore, in the American Journal of Respiratory and Critical Care Medicine, found that the dietary fiber from fruit—and possibly foods with soy—could reduce the occurrence of chronic respiratory symptoms, with phlegm among them.)

According to Dr. Mattewal, other helpful ways to reduce phlegm include:

• Avoiding smoking and vaping
• Practicing good oral hygiene to reduce the risk of infection
• Exercising regularly, which can help improve lung function and get rid of mucus in your airways
• Elevating your head while sleeping (which he notes is especially helpful for those with GERD)
• Investing in a humidifier to keep the air moist, taking care to clean it regularly since buildup of mold and bacteria can cause breathing issues

FAQs

What causes excessive phlegm?

“Increase in sputum production can be due to infectious or noninfectious causes,” Dr. Mattewal says. “Lungs produce more mucus to protect themselves.” Per the National Cancer Institute, chronic lung disease and various environmental triggers—including but not limited to smoke, dust, and pollution—can also cause phlegm to build up. The result: chest discomfort and your best effort to hack it all up and out of your system.

Certain foods can cause phlegm, too, though precise dietary triggers will vary from one person to the next. Dehydration is another culprit, as it causes mucus to build up and thicken.

Excessive phlegm may also be a symptom of acid reflux and GERD. These conditions “induce stomach acid to flow into the esophagus, causing irritation,” Hernandez says. “This activates the body's anti-inflammatory response by increasing mucus production.”

What causes phlegm after eating?

If you have excess phlegm after eating, Hernandez says a food allergy or sensitivity may be present. “Certain foods can trigger allergic reactions or sensitivities, leading to increased mucus production as the body attempts to protect itself,” he explains. Dehydration, acid reflux, or GERD may also be behind your post-meal phlegm buildup.

What naturally brings up phlegm?

Fortunately, there’s no shortage of natural remedies to bring up phlegm and improve congestion. Per Dr. Mattewal, the best of the bunch includes:

• Fluids (especially warm ones, such as herbal teas and warm water with lemon and honey)
• Salt water gargles, which will simultaneously help clear mucus and soothe a sore throat
• Anti-inflammatory spices and herbs, such as turmeric and peppermint
• Steam inhalation (with or without essential oils such as eucalyptus)
• Running a humidifier
• Exercising regularly

What drinks remove mucus from the body?

Dr. Mattewal says that water and fluids in general will help you stay hydrated, thereby helping to thin and expel mucus. For more robust and flavorful support, he suggests sipping on warm water with lemon and honey, as well as herbal teas, such as those with ginger, peppermint, turmeric, or thyme.

Why do I have a lot of phlegm but I'm not sick?

Fun (but kinda gross) fact: The texture and color of your mucus can help you pinpoint what’s actually behind it. For instance, clear mucus is typically normal—but if it’s also drippy you might have a mild cold or allergies. Yellow mucus is also linked to a cold, whereas green mucus could point to a fever or sinus infection. “Changes in color and consistency of sputum can be an indicator of certain breathing conditions,” Dr. Mattewal adds.

“Certain chronic lung diseases like chronic obstructive pulmonary disease (COPD), chronic bronchitis, asthma, bronchiectasis, and cystic fibrosis can also increase in sputum production,” he continues. Again, acid reflux and GERD can also trigger excess phlegm.

Potential sickness and infection aside, you might be sensitive to foods that cause phlegm. In addition, Dr. Mattewal notes that you might have a lot of phlegm due to:

• Exposure to environmental irritants such as air pollution and chemical fumes
• Allergies to pollen, dust, dander, mold, etc.
• Smoking, vaping, or secondhand smoke

Does drinking lots of water thin mucus?

Yes, staying hydrated with water and plenty of fluids is an expert-approved tip to thin mucus and remove phlegm from the body.

—reviewed by Jennifer Gilbert, MD, MPH