Milk, mucus and cough


IMPORTANT The information provided is of a general nature and should not be used as a substitute for professional advice. If you think you may suffer from an allergic or other disease that requires attention, you should discuss it with your family doctor. The content of the information articles and all illustrations on this website remains the intellectual property of Dr Raymond Mullins and cannot be reproduced without written permission.

Some people complain that milk makes their nose run, coats their throat and triggers coughing. Does milk really make the body produce more mucus?

Everyone has mucus
Mucus consists of water, salt and various proteins that help to trap germs and particles of dirt. Antibacterial enzymes and proteins called antibodies also help to kill germs and protect from infection. Produced by cells within the nose, sinuses and lung, mucus is moved towards the back of the throat by microscopic "hair cells" (cilia) where it is then swallowed.

Mucus can irritate
Too much mucus can make the nose run or drip down the back of the throat, leading to "post-nasal drip". Typically caused by infections or allergy, excessive mucus can trigger cough, sore throats and husky voice.

Thick, dry mucus can also irritate the throat and be hard to clear. Dry mucus is more common in older people and in dry inland climates. Air conditioning, winter heating and dehydration can aggravate the condition. Some medicines such older antihistamines, antidepressants and blood pressure medicines can do so as well.

Milk does not trigger mucus production
Some people complain that when they have dairy products, their throat feels coated and mucus is thicker and harder to swallow. Recent research has shown that these feelings are due to the texture of the fluid and occur with similar liquids of the same "thickness" (viscosity). This "coating effect" is not due to increased production of mucus. Furthermore, symptoms are short-lived and not related to allergy.

Milk does not cause middle ear infections
Middle ear infections (otitis media) are very common in early childhood. Infections are even more common when children suffer from allergic rhinitis ("hay fever") as well. This is because allergic inflammation causes swelling in the soft tissue of nose and around the opening of the eustacian tube ("ear canal"). Swelling interferes with drainage of the middle ear and sinuses, and like water in a stagnant pond, infection is more likely.

Children with true milk allergy sometimes appear to suffer from more frequent infections. This is not because milk causes infection, but rather because children with food allergy are more likely to suffer from an allergic nose as well.

Eliminating dairy product does not help asthma or hay fever
Asthma and hay fever are normally triggered by substances that we inhale, such as pollens, dust mite, mould spores or animal dander. With the exception of isolated cases of asthma or hay fever triggered by inhaling food allergen, swallowed food rarely triggers respiratory symptoms in isolation. Food allergy is almost always accompanied by obvious symptoms of anaphylaxis, such as severe hives, throat or tongue swelling or a drop in blood pressure ("shock") as well.

Recent studies have shown that milk has no effect on lung capacity, and does not trigger symptoms in patients with asthma any more than placebo. When patients complain of cough after having cold milk, it is usually due to breathing in cool air as they drink, and usually disappears if they warm the milk first. If you feel better by avoiding dairy in your diet, that’s fine, but don’t swap a stuffy nose for soft bones/osteoporosis later in life, or even worse, risk your child’s nutrition by taking them off an important nutrient in the mistaken belief it will help their infections.

The bottom line
Milk and dairy products are an important source of calcium and other minerals needed for strong teeth and growing bones. Cutting out important foods for long periods without medical supervision can adversely affect nutrition and is of no benefit in asthma or hay fever. Restricted diets can also distract efforts away from more productive areas such as allergen avoidance. And there is not a single published article in any peer reviewed medical journal or blinded trial showing any evidence of benefit but lost of evidence to the contrary!


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Last reviewed 28 January 2010