I've heard that you shouldn't drink milk when you have a cold because it increases phlegm. Is this true?
Answer From Julie Baughn, M.D.
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.
June 25, 2021
From Mayo Clinic to your inbox
Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health.
ErrorEmail field is required
ErrorInclude a valid email address
To provide you with the most relevant and helpful information, and understand which
information is beneficial, we may combine your email and website usage information with
other information we have about you. If you are a Mayo Clinic patient, this could
include protected health information. If we combine this information with your protected
health information, we will treat all of that information as protected health
information and will only use or disclose that information as set forth in our notice of
privacy practices. You may opt-out of email communications at any time by clicking on
the unsubscribe link in the e-mail.
Thank you for subscribing!
You'll soon start receiving the latest Mayo Clinic health information you requested in your inbox.
Sorry something went wrong with your subscription
Please, try again in a couple of minutes
See more Expert Answers
- Balfour-Lynn IM. Milk, mucus and myths. Archives of Disease in Childhood. 2019; doi:10.1136/archdischild-2018-314896.
- Koren Y, et al. Respiratory effects of acute milk consumption among asthmatic and non-asthmatic children: A randomized controlled study. BMC Pediatrics. 2020; doi:10.1186/s12887-020-02319-y.
- Cifelli CJ, et al. Association of yogurt consumption with nutrient intakes, nutrient adequacy, and diet quality in American children and adults. Nutrients. 2020; doi:10.3390/nu12113435.
- Lehtoranta L, et al. Role of probiotics in stimulating the immune system in viral respiratory tract infections: A narrative review. Nutrients. 2020; doi:10.3390/nu12103163.