Milk, Mucus and Cough

Frequently Asked Questions

This document has been developed by ASCIA, the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand. ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice.

For patient or carer support contact Allergy & Anaphylaxis Australia or Allergy New Zealand.

ASCIA PC Milk Mucus Cough FAQ 2024116.74 KB

Q 1: What is mucus?

Mucus consists of water, salt, proteins and enzymes that help trap germs and particles of dirt, and is produced by cells in the nose, sinuses and lungs. Antibacterial enzymes and antibodies in mucus protect from infection by recognising germs so they can be removed by the rest of the immune system.

Q 2: What causes an increase in mucus?

Too much mucus is usually caused by infections or allergy and can make the nose run or drip down the back of the throat (post-nasal drip). It can trigger a cough, sore throat and a husky voice.

Thick, dry mucus can irritate the throat and is hard to clear. It is more common in older people and in dry, inland climates. It can get worse with air conditioning, heating, dehydration and some medications.

Some people believe that when they drink milk, their throat feels coated, and their mucus is thicker and harder to swallow. Research has shown that this is not due to the body producing more mucus. It could be due to the texture of the fluid, as this happens with other liquids of the same thickness.

Q 3: Does milk cause middle ear infections?

Milk does not cause middle ear infections, which are common in young children especially if they have allergic rhinitis (hay fever). Allergic rhinitis can cause swelling in the nose and around the opening of the ear canal. This can get in the way of the proper drainage of the ear.

Children with cow's milk (dairy) allergy may have middle ear infections more often. This is because children with food allergy (such as dairy) are more likely to have allergic rhinitis and other allergies.

Q 4: Do dairy products trigger asthma or allergic rhinitis?

Asthma and allergic rhinitis are normally triggered when pollen, dust mite, mould or animal dander allergens are inhaled. Dairy products rarely trigger asthma or allergic rhinitis. When they do, other allergy symptoms, such as hives, throat or tongue swelling, or a drop in blood pressure may occur.

Studies have shown that dairy products have no effect on how much air the lungs can hold and rarely trigger asthma symptoms. When people report coughing after having cold milk, it is usually due to breathing in cool air as they drink. When the milk is warmed, there is usually no cough.

Q 5: Should a person with allergic rhinitis and asthma continue to have milk in their diet?

Dairy products are an important source of calcium and other minerals needed for growth and strong bones and teeth. Removing cow’s milk from a diet can limit choices and may negatively affect nutrition.

Diet restrictions do not benefit most people with asthma or allergic rhinitis and can distract from avoidance of other allergens. If cow’s milk avoidance is thought to be needed, see a dietitian for advice.

Content updated August 2024

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