Does milk worsen a cough?

October 11, 2025 •

3 min read

Despite a widespread and long-held belief, scientific evidence consistently shows that drinking milk does not increase the amount of mucus your body produces. So, does milk worsen a cough, or is the sensation of thicker phlegm just a perception issue rooted in a centuries-old misconception?

Quick Summary

Scientific research debunks the myth that milk increases mucus or worsens a cough. The sensation of thicker phlegm is due to milk's texture combining with saliva, not increased production. Hydration is key to thinning mucus.

Key Points

No Scientific Link: Decades of research have shown no statistically significant link between milk consumption and increased mucus production or respiratory congestion during a cold.
Sensory Effect, Not More Mucus: The perception of thicker mucus after drinking milk is a temporary sensation caused by its texture mixing with saliva, not an increase in phlegm.
Myth Origin: The idea that milk causes mucus dates back centuries and has been mistakenly perpetuated, despite modern scientific evidence to the contrary.
Hydration is Key: The most effective way to manage mucus and soothe a cough is to stay properly hydrated with warm fluids like water, herbal tea, or broth.
Nutritional Value: For most people, dairy products like milk provide important nutrients and can be safely consumed while sick, especially if appetite is low.
Alternative Soothers: Natural remedies like honey, ginger tea, and steam inhalation are proven to help soothe an irritated throat and relieve a cough.

The Origins of a Persistent Myth

The belief that consuming milk and other dairy products should be avoided during a cold because they cause an increase in phlegm has been around for centuries. This myth is often traced back to a 12th-century physician and has been reinforced over generations through popular culture and childcare literature. Despite modern research, this perception continues to influence people's dietary choices when they are sick.

The Science Debunks the Milk-Mucus Link

Modern medical studies have consistently shown that dairy consumption does not lead to excessive mucus production.

Clinical Evidence

Numerous controlled studies have found no link between drinking milk and increased mucus in the respiratory tract. A 1990 study, for instance, showed no significant difference in nasal secretions between cold sufferers who drank milk and those who didn't. A review in Archives of Disease in Childhood concluded there is "no evidence" that milk increases mucus and advised healthcare professionals to correct this myth.

The Placebo Effect

Interestingly, some research suggests that the belief that milk causes more mucus can influence reported symptoms. People who already hold this belief may report feeling thicker secretions or needing to clear their throat more often after drinking milk. However, these subjective reports are not supported by actual physiological increases in mucus production.

The Sensory Effect: Why it Feels Thicker

If milk doesn't increase mucus, why the sensation of thicker phlegm? This is due to how milk's unique texture interacts with saliva. Milk is an emulsion that, when mixed with saliva, can temporarily increase the viscosity of saliva, creating a brief thickening or coating feeling.

Understanding the Perception

Oral Viscosity: The interaction of milk and saliva causes a temporary coating sensation in the throat, which can lead to more frequent swallowing or throat-clearing, often misinterpreted as increased mucus.
Texture vs. Volume: The feeling is about a change in mouthfeel and texture, not a greater volume of respiratory mucus. Studies using blind tests with alternatives like soy milk have shown similar reported symptoms in those who believe milk causes mucus, suggesting the effect is related to texture perception.

Effective Remedies for Coughing

Instead of avoiding nutritious dairy, focus on proven ways to soothe a cough and manage mucus. Staying hydrated is essential for thinning mucus and comforting a sore throat.

Natural Remedies for Soothing a Cough

Honey: Has anti-inflammatory and soothing properties. A teaspoon of honey can provide relief (avoid for children under 1).
Warm Fluids: Drinks like herbal teas, warm water with lemon, or broths help thin mucus and soothe the throat.
Steam Inhalation: Using a humidifier or taking a hot shower can help moisten airways and loosen phlegm.
Saltwater Gargle: Can help soothe an irritated throat.
Ginger: Known for anti-inflammatory effects, ginger tea may help ease a cough.

Cow's Milk vs. Alternative Drinks for Cough Relief


Feature	Cow's Milk	Herbal Tea / Warm Fluids
Effect on Mucus Volume	No increase in production; no effect on respiratory mucus.	Thins mucus, making it easier to clear.
Sensory Effect	Creates a temporary feeling of thicker saliva/coating due to milk's emulsion interacting with oral enzymes.	Soothes the throat and promotes hydration without the coating effect.
Nutritional Benefits	Good source of calcium, protein, and vitamins. Provides calories and nutrients, especially important if you have a poor appetite.	Provides hydration and can offer additional anti-inflammatory benefits depending on the type (e.g., ginger).
Best Use for Cough	Can be consumed as part of a balanced diet. If warm, it can be soothing for a sore throat.	Excellent for actively soothing the throat and thinning congestion.

Conclusion

The idea that milk worsens a cough by increasing mucus is a myth not supported by scientific evidence. The feeling of thicker phlegm is a temporary sensory effect from milk interacting with saliva, not an increase in mucus production. For most individuals, drinking milk while sick is safe and can provide nutrients. If the texture is bothersome, hydrating alternatives like warm tea or water are good options. Focus on proven remedies such as hydration, rest, and warm fluids to manage your cough. For more information on respiratory health, consult reliable sources like the National Institutes of Health.

Frequently Asked Questions

No, scientific studies have repeatedly shown that milk does not increase the production of phlegm or mucus in the respiratory tract. The feeling of thicker phlegm is a temporary sensation caused by milk's creamy texture mixing with saliva.

The creamy texture of milk can cause saliva to thicken briefly, creating a coating sensation in the mouth and throat. This sensation, and not an actual increase in mucus, can make you feel like your cough is worse, though it is not physiologically affecting your condition.

Yes, the idea that milk increases mucus production is a persistent myth that has been debunked by scientific research. Studies have found no correlation between milk intake and increased respiratory congestion.

No, warm milk is not bad for a cough and can actually be soothing for a sore throat for some people. If the creamy texture bothers you, however, you can choose another warm liquid like herbal tea.

Warm fluids like water with honey and lemon, herbal teas (ginger, peppermint), or clear broth are excellent for a cough. They help to hydrate and thin mucus, making it easier to clear from your throat.

Yes, milk is a valuable source of nutrients and can be given to children with a cough. Unless the child has a diagnosed milk allergy, there is no need to restrict their dairy intake based on the false belief that it increases mucus.

There is no scientific evidence to support the claim that milk consumption triggers or worsens asthma symptoms in non-allergic individuals. Respiratory symptoms are rarely the sole manifestation of a food allergy.