EDIT: 12/2019 Since this question still occasionally gets hits:

In the years since I asked this question I found out that I have sleep apnea. I also learned about the effects of mouth breathing which significantly increases your risk for a variety of problems, such as this one. I've been doing myo-functional therapy exercises (with this therapist), learning to play the Didgeridoo, and reading and practicing the exercises from the book "The Oxygen Advantage". I also now sleep with mouth tape. I've still got a ways to go, but my journey in learning to breath better has improved this quite a bit.

I have a bit of an odd question, whenever I do cardio workouts that get my heart rate up and breathing hard I get phlegm buildup in my throat and my nose starts running. It's not a huge amount but it's enough that I wind up spitting and wiping my nose frequently during workouts (the snot sometimes comes out greenish but mostly clear).

This has been happening pretty consistently for as long as I can remember. I regularly run, bike, swim, and do pilates (typically 2 - 3 times a week for each though I've been falling off lately with pilates). Pilates is the only exercise that doesn't cause this because it's a slower pace more focused on core strength and flexibility so my heart rate doesn't get very high and I'm never pushed to breathing heavily. It's also not effected by workout frequency, the times in my life where I've been working out less/not at all have not decreased this when I start up again.

Does anyone know what would cause this and what I could do about it?

  • Do you breath thru your nose or mouth?
    – DFG4
    Commented Aug 17, 2011 at 17:51
  • Swimming is always in through the mouth out through the nose. While running and biking I start out breathing in the nose and out through the mouth but inevitably switch to mostly through mouth. It's hard for me to say if that's because stuff starts coming out my nose so I feel like I'll just be sucking it in if I breath in through my nose or if the switch happens before that. I'll pay more attention this evening and see.
    – asm
    Commented Aug 17, 2011 at 19:15
  • Not an odd question at all. Very valid and the condition is quite common. Commented Aug 17, 2011 at 20:36

7 Answers 7


I have a new enemy and its name is CHEESE

Believe it or not, this is some what common. It frustrated me for quite some time before I found the cause. DAIRY.

I used to have a cup of greek yogurt every day as well as some quantity of milk and ice cream throughout the week. Every single time I would get in the pool, I would be annoyed with phlegm.

Try cutting out or reducing dairy (cheese, milk, yogurt, etc.) for a few days and see if it gets better. It certainly did with me. I still have eggs or egg substitutes almost daily and that does not seem to bother me.

Here is a supporting article from livestrong.com that supports dairy as a cause and accelerator of phlegm is some people.

Also, it may be a intolerance to lectin (which is a component of dairy). But, it may not be dairy that causes your excess mucus. Other sources of lectin are legumes, glutens, and potatoes. More on lectin intolerance can be found here.

  • Would you have any sources for this or is it just based on your own experience?
    – Ivo Flipse
    Commented Aug 17, 2011 at 21:07
  • @Ivo: I've added two sources, but yes it is also based on my own experience. Commented Aug 18, 2011 at 0:19
  • Hmm this could be my problem, I typically have a lot of dairy intake during the day as well.
    – asm
    Commented Aug 18, 2011 at 11:42

This (phlegm) happens to me from allergies. Allergies can be exacerbated or become more noticeable during exercise. Examples from my case: When my allergies are less controlled overall, it will effect every form of working out, but there are also specific triggers. When jogging in the fall or after rain, there is more mold and mildew. When swimming, my already sensitive sinuses are exposed to chlorine and rapid pressure changes. Since you suspect dairy as well, consider visiting an immunologist.


Actually, I think that phlegm production is normal in cardio workouts, the variance being: a) the individual, and b) the amount produced. My girlfriend did a lot of heavy duty cardio routines and she was tormented with tons of phlegm from it, and now that I have started doing them myself, I also have found I have the same problem, while others I know seem to have little problem this this issue. I also found that if I abstain from dairy products the amount of mucus is diminished. It may be, since we are all different physiologically, that our bodies respond in a unique way to exercise. But basically, even with the annoyance of excess mucus production, cardio is well worth the effort.


Similar things would happen to me while doing cardio in winters. For me, it happened due to sinusitis. My sinuses would burn when I inhale comparitively cold and dry air at a faster rate (as in increased rate of breathing during exercise). It causes me mild headache in addition to phlegm and runny nose.

I found that using certain specific oils (they call it 'nasya' in ayurveda, don't want to be advertising brands here) to instil in nose helped moisturize the nasal passage and my sinuses and nosy don't act up anymore. I found that doing nasya is great as expectorant and helps me 'do normal' during cardios without phlegm and stuff.

However, you would want to be sure that it is due to sinusitis before you decide on trying out nasya.

hope this helps....


I have exactly the same problem, except it also happens every night in my sleep. I wake up coughing up plegm, and I get it when I excercise. Might try the no dairy thing and see if it helps. No nose spray or allergy shots have helped. Every doctor seems to recommend nasal sprays but they are worthless to me. Antihistamines seem to be the only cure, and I find I need more of them every day.

  • 3
    This reads more like a comment than an answer.
    – Alec
    Commented Sep 25, 2015 at 6:27

Look up "10 Signs You Have Candida Overgrowth & What To Do About It" this really helped my condition. You can find pills to help fight this issue.

  • 1
    This would be a more useful answer if it had a link people could follow, instead of having to Google themselves. Ideally, the parts of the link that answer the question would be included in the answer in case the other document goes away.
    – Noumenon
    Commented Oct 8, 2016 at 22:28

Are you a smoker? I've been training for several years and I'm a daily smoker. Every other day, between weight training, I like to do long cardio session with several layers of cloths and try to sweat as much as possible. Typically ending with stretching and sauna. For me, as gross as it might sounds, the best part comes when I feel that phlegm build up and spit it out. I've had done radios of my lungs in the past for other medical reasons and the doctor couldn't even tell I was smoking, to my surprise.

I understand it can bother you, but on the better side of things, aerobic exercices speed up the elimination of body wastes and toxins. If it's comming out while doing cardio, maybe your simply doing your body a favor by expelling exceeding phlegm.

I would also try to rinse your sinuses with salty nasal spray before training. It could maybe get rid of the excess or limit inconveniences while training.

Good luck!

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