Is dairy bad when you have a cold? The surprising truth about milk, mucus, and illness

October 18, 2025 •

5 min read

According to a systematic review of studies, there is no scientific evidence to support the popular belief that consuming dairy products increases mucus production or worsens cold symptoms. The question, 'Is dairy bad when you have a cold?', is one of the most persistent health myths, but it's important to separate fact from perception, especially when proper nutrition is key to recovery.

Quick Summary

The belief that dairy increases mucus during a cold is a widespread myth. Scientific studies show no link between dairy consumption and increased mucus production. The sensation of thicker phlegm is often due to milk's texture coating the mouth and throat. Consuming dairy can be beneficial for hydration and calories when sick, so long as there is no allergy or intolerance.

Key Points

The 'Milk-Makes-Mucus' Idea is a Myth: Numerous scientific studies have disproven the popular belief that dairy consumption leads to increased mucus production or worsens cold symptoms.
Thickened Sensation is Due to Texture: The feeling of thicker phlegm or a coated throat after drinking milk is a sensory perception caused by the liquid's creamy texture mixing with saliva, not an actual increase in mucus.
Dairy Can Be Nutritious When Sick: For individuals without an allergy or intolerance, dairy products provide essential nutrients like protein, calcium, and vitamins A and D, which are important for immune support and overall energy during illness.
Hydration is Crucial: Milk contributes to overall fluid intake, which is vital for staying hydrated when you have a cold. However, plain water, broth, or herbal tea are also excellent options.
Listen to Your Body: If consuming dairy makes you feel personally uncomfortable or exacerbates symptoms due to an intolerance, it is reasonable to avoid it. But this is a matter of personal comfort, not a medically necessary restriction for everyone.
Consider Soothing Options: Cold dairy products like ice cream or a smoothie can be soothing for a sore throat, while warm milk can also provide comfort.

Is it a myth or a fact? The milk and mucus connection

The notion that drinking milk when you have a cold causes excess phlegm is a belief that has existed for centuries. For many, the creamy texture of milk feels like it's coating the throat, which is then mistaken for an increase in mucus. This sensory perception, however, is not the same as a physiological increase in mucus secretion. Studies dating back to the 1990s have investigated this claim, and time and again, research has shown no statistically significant link between dairy intake and increased mucus production or respiratory congestion in people with a cold.

What the science says about dairy and colds

One landmark study involved volunteers infected with the common cold virus (rhinovirus-2). Participants were monitored for their dairy consumption and nasal secretions over a ten-day period. The researchers found no correlation between the amount of milk consumed and the weight of nasal secretions. In fact, those who believed in the 'milk-makes-mucus' myth often reported feeling more congested, even though their objective mucus measurements were no different from those who didn't believe the myth. This suggests that for many, the effect is largely psychological or related to the texture of the beverage, not the content.

More recently, a double-blind trial compared the effects of cow's milk with a soy-based drink that mimicked milk's mouthfeel. Participants who believed milk caused mucus reported similar sensations of a coating in their mouth and throat after consuming either beverage, demonstrating that it's the texture, not the dairy itself, that creates the perception of increased phlegm.

Potential benefits of dairy when you're sick

Far from being harmful, consuming dairy when you have a cold can actually be beneficial, provided you don't have an intolerance or allergy. During an illness, it can be difficult to maintain an appetite, and dairy products offer a comforting and nutrient-dense source of energy.

Hydration: Milk is a fluid that contributes to your overall hydration, which is crucial when you're sick. Staying hydrated helps keep mucus thin and easier to manage, counteracting the effects of dehydration from fever or a reduced fluid intake.
Nutrient Boost: Dairy products are rich in essential nutrients like protein, vitamins A, D, and B12, as well as calcium and zinc. These nutrients are vital for supporting your immune system and providing energy when your body is working hard to fight off an infection.
Soothing a Sore Throat: Cold or frozen dairy products, like ice cream or a frozen yogurt smoothie, can be incredibly soothing for a sore throat. Warm milk with honey is another comforting option that can help ease throat irritation.

What to consider before consuming dairy

While the mucus myth is largely debunked, there are specific situations where you might want to reconsider dairy intake when ill. It all comes down to listening to your body and your own specific health needs.

Lactose Intolerance: If you are lactose intolerant, consuming dairy can cause digestive issues such as bloating, gas, and diarrhea, which can exacerbate feelings of illness. Opting for lactose-free alternatives or avoiding dairy is the best choice in this case.
Dairy Allergy: A genuine dairy allergy is different from lactose intolerance and involves an immune system reaction. Symptoms can include hives, swelling, or difficulty breathing, and in rare cases, respiratory symptoms can be triggered. If you have a known dairy allergy, you should avoid it completely.
Personal Comfort: For some individuals, the perception of thickened phlegm after consuming dairy is genuinely uncomfortable. If eating dairy makes you feel worse, there's no harm in avoiding it for comfort, even if it's not actually increasing mucus production. Plenty of other foods and drinks can provide the necessary nutrients and hydration.

Comparison of Dairy vs. Dairy Alternatives for Colds


Feature	Dairy Products (Milk, Yogurt)	Dairy Alternatives (Almond, Oat Milk, Broth)	What to consider during a cold
Mucus Perception	Can create a feeling of thicker saliva and a throat coating due to texture, but does not increase production.	Do not typically create a 'coating' sensation.	Listen to your body; if the feeling is uncomfortable, opt for alternatives.
Nutrient Content	Excellent source of protein, calcium, Vitamin D, and B12 to support the immune system.	Varies by type; many are fortified with calcium and Vitamin D, but may lack other nutrients found naturally in milk.	Dairy provides a complete nutritional profile that can help recovery if tolerated.
Hydration	Contributes to fluid intake, which is essential when sick.	Excellent sources of hydration; options like broth also replenish electrolytes.	All fluids are good for hydration, but avoid sugary drinks, alcohol, and caffeine.
Sore Throat Relief	Cool milk, ice cream, and warm milk with honey can be very soothing.	Broth, herbal teas, and warm lemon water with honey can effectively soothe a sore throat.	Personal preference for warm vs. cold fluids is key; both can provide relief.
Digestive Issues	Can cause discomfort for those with lactose intolerance or a milk allergy.	Suitable for those with dairy intolerances or allergies.	Avoid dairy if it causes digestive upset, as this can worsen your overall feeling of sickness.

Conclusion

The bottom line is that the widespread belief, is dairy bad when you have a cold, is a myth not supported by scientific evidence. For most people, dairy consumption does not increase mucus production. The perception of thicker phlegm is a result of the creamy texture of milk mixing with saliva, not an overproduction of mucus by the body. Dairy products are a valuable source of nutrients and calories, which are especially important when you're under the weather and might not feel like eating. As long as you don't have a specific milk allergy or lactose intolerance that causes digestive upset, feel free to enjoy dairy products like a soothing smoothie, yogurt, or even ice cream to help manage your symptoms and maintain your strength during a cold. The most important factors for a speedy recovery remain proper hydration, rest, and listening to your body's signals.

BDA - British Dietetic Association is a helpful source for further information on dairy's nutritional benefits.

Frequently Asked Questions

No, this is a long-held myth that is not supported by scientific evidence. Research has shown that drinking milk does not cause your body to produce more mucus. The feeling of thicker phlegm is a sensory effect from the milk's creamy texture mixing with saliva.

For most people without a dairy allergy or intolerance, dairy products are unlikely to harm a cold and can be beneficial. They offer important nutrients and calories, which can be helpful if your appetite is low. The key is to listen to your body and consume what feels comfortable.

This is often a psychological or textural effect. The creamy consistency of milk can mix with saliva, creating a coating sensation in the mouth and throat that can be mistaken for thicker mucus. This sensation, however, does not correspond with an actual increase in mucus secretion.

Yes, if you are lactose intolerant, it is best to avoid dairy when you have a cold. The digestive discomfort associated with lactose intolerance, such as bloating and gas, can add to the unpleasantness of being sick.

Yes, chilled or frozen dairy products can actually be very soothing for a sore throat. They can provide temporary pain relief and offer a source of fluids and calories when swallowing is difficult.

Excellent alternatives include water, clear broth, herbal teas, or dairy-free smoothies. Broths are particularly good for hydration and electrolytes, while warm teas can be very comforting.

No, since dairy does not cause or worsen a cold, avoiding it will not shorten the duration of your illness. The most important factors for recovery are rest, staying hydrated, and a balanced, nutritious diet.