The belief that milk increases mucus production dates back hundreds of years and continues to be a widely held belief, despite the fact that there is no scientific research demonstrating that drinking milk leads to increased mucus production in the airways or throat, or a worsening of cold or asthma symptoms. Studies have failed to demonstrate any significant link between the two. In fact, though many people reduce milk intake when they have a cold, one clinical trial showed that milk and dairy food intake was not associated with an increase in upper or lower respiratory tract symptoms of congestion. Studies have found milk intake was not associated with increased nasal secretions, coughing, nose symptoms or congestion.

Many people confuse the temporary, slight thickening of saliva after drinking milk with mucus. This thickening, which may coat the throat and give the perception of more mucus, does not cause the body to produce more mucus. In fact, drinking milk may actually speed up the recovery process, as drinking fluids is important when cold symptoms are present. Frozen dairy foods and fruit smoothies may also soothe a sore throat and provide important calories and nutrients when a person isn’t up to eating much else.

References

Pinnock CB, Graham NM, Mylvaganam A et al. Relationship between milk intake and mucus production in adult volunteers challenged with rhinovirus-2. Am Rev Respir Dis. 1990;141(2):352–356.

Wüthrich B, Schmid A, Walther B et al. Milk consumption does not lead to mucus production or occurrence of asthma. J Amer Coll Nutr. 2005;24(6 Suppl):547S–555S.

Thieme M. Dairy recommendations for ill pediatric patients. J Pediatr Nurs. 2014;29(2):180–181. doi: 10.1016/j.pedn.2013.08.008