Does milk cause phlegm?

Dear Cecil and M.D.s:

I am besieged by motherly and anecdotal testimonials that claim milk causes phlegm (sometimes, they say milk causes mucus, in general). The anecdotes often come from vocalists (the wussy kind who always have to have a glass of water with them on stage) who say that it creates too much phlegm and clogs up their chords. Mom always wanted to withold my milk during colds out of some fear that I’d become too congested.

Now, the scientist in me says, “What is it in milk that causes the production of all this lung mucus?” Mom has learned to ignore me when I question one of her religious beliefs like this, and the prima donnas just say, “I don’t know, it just does for me.”

Is it the calcium or the fortified vitamin D that tells the mucus producing glands to go at it? Does lactose lead to lung lactation? Or, are mom and the songbirds fooling themselves in thinking that white drinks create white bodily fluids? Or is there no connection at all?

Set me, mom, and the lounge singers straight on this, Cece.



We are not doctors…but I can give you my own personal opinion.

I have found when I have the beginnings of a head cold (running nose, cough…) to avoid milk products. It took me about 1000 colds to finally learn this and it cuts my suffering down considerably. If I am afflicted with a bad cough, besides medicine and cough drops, I drink tons of hot tea to help relax the throat muscles.

The rest of your question, my answer is simple: I dunno. Ask your doctor.

Bigamy is having one wife to many. Monogamy is the same. - Oscar Wilde

As a sometime singer, I can confirm milk’s effects on the vocal cords. It isn’t due to milk’s stimulating the body to produce its own slime, though; the mucilage that gums up the vocal cords is present in the milk itself. It isn’t a “wussy” thing, it’s just that singers know to avoid things that mess up their instrument, just like one might try not to spill syrup on one’s guitar strings.

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Da Chef

Chef Troy wrote:

I sing, too, though not professionally, and I slug down the bovine nectar all the time. I don’t notice its effects (though, I may have built up resistance :slight_smile: ).

Anyway, liquid refreshments don’t pass through the larynx or over the instrument (i.e., the vocal chords, to the tone deaf) – so how could milk leave a slick there?


Just my personal experience: I cough of gobs of phlegm after eating ice cream or drinking milk. My mom told me she heard that can be a symptom of a milk allergy. But I haven’t consulted a physician because I don’t eat ice cream very often, and I abhor milk. I’ll worry about it if I go into anaphylactic shock :wink:

“I hope life isn’t a big joke, because I don’t get it,” Jack Handy

Okay Moriah…I admit I have only my own experience to back up my assertions, but I’ve also heard the same from MANY other singers of my acquaintance.

You are of course right to point out that food does not pass through the larynx, as it is protected by the epiglottis and by muscular contraction when something is being swallowed. However, what SEEMS to happen when I drink milk is that it makes my saliva very thick and ropy – maybe it’s some kind of chemical reaction, I don’t know. Ropes of sticky milk-spit hybrid attach themselves in the pharynx and often the epiglottis itself, and impede the normal resonance of the human voice. Hence the tendency of a human voice to sound bubbly and thick when the person speaking is phlegmy (due to milk or not.)

One one occasion I was called out to a last-minute audition right after having eaten a couple of bowls of cereal (the dinner of champion college students everywhere – at least when you want a change from ramen :slight_smile: ); I was able to counteract the dreaded lactic ooze by gargling with lemon juice. Acids cancel bases, you know. One of the few things from high school chemistry that ever did me any actual good.

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Da Chef

Moriah, I can’t speak for everyone else, but milk and milk products give me sinus headaches if consumed in any kind of quantity (ie: 2 bowls of cereal a day for 3 days). Yeah, I know, you didn’t need to know this, but I have to stick with your mom at least in the theory that it does SOMETHING. It only took me 4 years to realize that the frequent headaches I was having were resulting from my favorite food, cereal (it’s not just for breakfast anymore!) with whole milk.

Sorry I can’t offer scientific evidence or research. I’ll search the net and let you know if I find anything!

Chef Troy wrote:

Actually, since that’s lactic acid, I think milk is acidic, not a base. However, if that was whole milk you were drinking, the lemon juice probably help cut any residual milk fat (i.e., cream). But then again, so would your saliva in time.

Maybe because I drink skim milk, I don’t notice any phlegmatic effects. On the other hand, I don’t remember any effects from when I used to drink whole milk, or eat ice cream which can be up to 40% fat.

And for all those of you who find milk produces reactions more severe than a mild mucus/phlegm build up (such as headaches, rashes, gobs of phlegm, upset stomach, etc…), then yes, you are allergic to milk. Try the new lactose free milk products (such as Lactaid) at your grocer. You can have cereal again!


Sorry, but as the inspector said to the fence builder, your post is flawed.

Lactic acid is not present in milk. It is in fact produced by the body, to wit:

The component that causes allergic reactions is lactose, aka “milk sugar.” milk is unquestionably a base rather than an acid, which is why it curdles when you add vinegar to it. If they were both acidic, there would be no reaction.

Anyway, it’s the proteins in milk that cause one’s saliva to become thick and ropy.

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Da Chef

Chef Troy writes:

Excuse me, but, huh? Where do you get that only bases react with acids? Consider the effects of acids on many pure metals, or on silicon (acids are used to etch IC chips, for example). I don’t think these are considered to be bases.

I suspect that the curdling of milk when mixed with acid has more to do with the denaturing of the protein, causing it to clump. I don’t think protein is particularly basic.

Unless a base is defined as ‘anything that reacts with an acid’. In which case, never mind.


If you read up a little higher, Rick, you’ll see that Moriah took issue with my applying the fact that acids neutralize bases and vice versa to the milk-phlegm issue by saying that milk was acidic and would therefore not be affected by lemon juice and its attendant citric acid.

I never said that only bases react with acids. I said that a) bases cancel (neutralize) acids, and b) that two acids don’t affect each other. There’s a big difference.

However, your point about the proteins clumping is well taken. Okay?

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Da Chef

In view of the famously nit-picky quality so many of this message board’s regulars display, I feel I should head off comments by saying that my assertion that two acids do not affect each other, I was referring specifically to changing their pH balances, (i.e. becoming more or less acidic or alkaline). So don’t flame me with proof that acid A causes acid b to change color or smell like bananas.

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Da Chef

Da Chef wrote:

Well, it doesn’t make my saliva thick and ropey.

So, if you were to pour a bit of milk in a dish, and then spit/drooled into it and stirred; are you saying that the mixture would become more viscous somehow? Or are your salivary glands now producing a thicker spittle when you drink milk?

Re: the lactic acid – Doh! :o Sorry for that horrendous gaffe. So, since milk is a base (anyone able to look up its Ph?) wouldn’t saliva break it up in the same way lemon juice does (since, I believe, saliva is acidic – but I’m not committing to that one)?

And if the saliva and milk mixture gets a bit thick – how does that cause phlegm in the lung or mucus in the larynx? Eating food causes much thicker spittle than drinking milk, and I don’t know of anyone claiming that food causes phlegm. Thick saliva doesn’t lead to phlegm in other culinary cases.

For those allergic to lactose, I can believe their milk complaints. But until there’s some stronger scientific explanation for how ‘milk causes phlegm’ I think I’m going with the hypothesis of old wives tale and psychosomatism.

Well, if it’s an old wives tale, it works. A few years back I had TMJ surgery, and was on a liquid diet for a couple of weeks. The second or third day back home, I started having trouble breathing. I talked to the doctor and he told me to stop drinking milk products, which did work.

Mastery is not perfection but a journey, and the true master must be willing to try and fail and try again

And since I had never heard of this phenomenon, it couldn’t have been psychosomatic

I never said that milk causes phlegm. In fact, with the exception of an allergic reaction (the symptoms of which I’m not familiar with) I don’t see how it could. The effects of milk on…well, I suppose I should limit it to MY singing voice…are achieved not by mucus in the larynx but by thick, mucilaginous spit in the pharynx (above the larynx) and on the epiglottis.

I have not tried drooling into a dish of milk, but it sounds like fun – with TV in reruns I’m looking for some excitement. Maybe I’ll give it a try.

At any rate, it seems that our respective positions on this so far have been (me) “it happens to me, so it must happen to others,” and (Moriah) “it doesn’t happen to me, so it must not happen to others.” I think my position is the more defensible of the two, especially given the anecdotal evidence from lots of others, in this thread and in real life.

Perhaps we can agree that the phenomenon does occur for some people, even if the mechanism by which it happens may be other than what those of us in the milk=mucilage faction believe it to be based on observation?

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Da Chef

I think the answer to this question (and your assertion that saliva is acidic sounds right to me – I believe the acidity of saliva is a major factor in the “biting on tinfoil=horrible pain” equation) is simply one of relative strength. Lemon juice is a much stronger acid than saliva and would therefore work more quickly.

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Da Chef

OK, I’ll be annoyingly nitpicky again:

According to the biochem department at Temple University, saliva is indeed slightly acidic at rest, but, when the glands are actively secreting, it is actually basic, with pH approaching 8. Here’s the link:

This link: , describes a nice experiment demonstrating that acidic saliva fails to perform its role in starch digestion.

So, if you spit into a bowl of milk, it might indeed curdle. However, when you have your milk and cookies, your mouth is filled with mildly alkaline drool.


Oh, and another fun link I found: .

According to this, milk is, in fact, slightly acidic, with a pH of 6.4.