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Cold symptoms: Does drinking milk increase phlegm?

Medically reviewed by Last updated on Jun 25, 2021.

Phlegm is the thick, sticky mucus that drips down the back of your throat when you have a cold. It's a combination of the normal protective fluid in your respiratory passages and debris related to your infection.

While it's commonly believed that drinking milk increases phlegm, the science doesn't back up the belief. Conclusions from research about milk and phlegm — a relatively small field of study — include the following:

  • Milk consumption and phlegm production among people with the common cold in a clinical study showed no increased phlegm associated with drinking milk.
  • Self-reported problems with mucus were the same between two study groups — one drinking milk and another drinking soy milk.
  • Children with asthma, who often avoid milk because of the increased-phlegm theory, experienced no differences in breathing symptoms whether they drank milk or soy milk.

The problem with milk may be a sensory trick. Milk and saliva in your mouth create a somewhat thick liquid that can briefly coat the mouth and throat. The sensation that lingers may be mistaken for increased phlegm.

Reasons not to avoid milk

A glass of cold milk or a few bites of frozen yogurt may, in fact, soothe a sore throat and provide some nutrients and calories at a time when you don't feel like eating. You might also try a nutrient-packed fruit and yogurt smoothie, which provides zinc, calcium, probiotics, vitamins, antioxidants and fiber.

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