What Are the Most Common Causes of Vomiting Mucus?

An illustration of a human stomach.
A bad cough may cause someone to vomit mucus.
Someone may vomit mucus as a result of a severe cold.
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  • Written By: Meghan Cunningham
  • Edited By: C. Wilborn
  • Last Modified Date: 15 April 2014
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Although sometimes unsettling and a bit scary, vomiting up mucus is fairly common. Rather than an actual illness, vomiting mucus is actually an effect that can be caused by a variety of factors. It may be caused by a severe cold, an upper respiratory infection, allergies, or a bad cough. Acid reflux may also be a cause.

Mucus is a fluid secreted by mucus membranes. The human body produces anywhere from a quart to a gallon (0.94 to 3.78 liters) of mucus a day. Mucus coats the walls of the nasal passages to collect particles, such as dust or pollen, that might irritate someone and cause him or her to sneeze. It also lubricates the air passages, making it easier to breathe, and coats the esophagus and stomach to protect these organs from stomach acid.

Sometimes, however, the body creates too much mucus, such as during a cold, an upper respiratory infection, an allergy attack, or a coughing fit. In these instances, the mucus leaks from the sinuses and runs down the back of the throat — called post nasal drip — or is coughed up from the lungs; it may then be swallowed and end up in the stomach. When a person swallows too much of this secretion, it can cause the body to begin vomiting mucus. Too much mucus or mucus that is too thick can cause nausea, and one of the body's natural responses is to trigger vomiting to ease that nausea.


In young children, one of the major reasons for vomiting mucus is due to their sensitive gag reflex. A child with a cold, allergies, or lung infection will secrete a great deal of mucus; that child may cough so forcefully trying to clear his or her airway that it triggers the gag reflex, and he or she vomits. In addition, children tend to swallow mucus rather than spitting it out or "coughing it clear" as adults do. This may occur when children have a severe infection, such as a sinus infection that creates thick, excessive secretions of mucus.

Another cause of vomiting mucus may be due to acid reflux or heartburn. Mucus coats the esophagus and stomach walls to prevent stomach acid from damaging or dissolving those organs. When one has acid reflux, the stomach acid backs up into the esophagus. In order to protect itself, the body produces more mucus secretions. This excessive secretion is often swallowed back down into the stomach, and when there is too much, a person might feel ill and vomit up the excess mucus.


Discuss this Article

Post 7

I will wake up in the morning, and sometimes throw up after coughing. It's a yellowish/greenish liquid which doesn't burn. I also randomly wake up with terrible heartburn. Thanks for the enlightening article. I'm going to work on the heartburn, and I've been taking allergy medicine which has been helping a bit.

Post 6

Does your baby drink water? I started giving my daughter water at night two days ago and she threw up all the mucus she had been swallowing tonight around 4 a.m. I'm glad I was awake. Otherwise, she might have choked on it in her sleep. She had a severe cough but all she could do was swallow the phlegm. She isn’t smart enough to spit it out yet. She’s only 13 months old.

I just think about how I feel when I forget to drink water and drink milk and other things like soda, etc. I get thick mucus. On top of the cold she had, I kind of put it together. I got her diet and sleeping perfect also during this water binge and I think I'm going to continue it. She isn’t coughing in her sleep anymore. That usually kept her awake. Since she threw up two hours ago, I'm just sitting here watching her while browsing the net about it.

Don’t slack on taking the time to feed your child nutritious things rather than just handing them a bottle. My daughter will act like she doesn’t want the bottle, but will devour some Gerber or cereal 80 percent of the time (she will eat my food anytime, even after she is full and I try to sneak my meal, but I always give her some just to boost the diversity of her diet and to fill her up). Sometimes though, she wants a bottle and she actually drinks water pretty well (better than I thought she would) with a little infant spoon of sugar added to about 3-4 ounces of water.

I try to get her sunlight anytime it’s warm out. I’m waiting for the weather to stop fluctuating so she doesn’t get sick again! I think that’s healthy for her. For some reason, the sun, the breeze, the buzzing and moving calms her cold down, but I'm crossing my fingers not trying to jump the gun, but I think her mucus is gone, after the amount she threw up. She had just eaten, but still only threw up mucus -- none of the cereal or rice and noodles she had eaten, just mucus immediately after she ate in the middle of the night. She didn’t want a bottle, which is unusual. She loves them at night because she doesn’t have to open her eyes. She was crying and coughing so hard I felt sad but I've always wanted her to spit that damn mucus out. I even tried timing it and fingering it out when she got that distinctive, good, hacking cough sound going but she swallows it fast. I can’t even see what it is with her tongue. The only thing I can think that could have also helped that I forgot to mention was I gave her an inhaler of proair hfr albuterol sulfate earlier in the night to just free the mucus (they say four times a day, but I don’t just so she doesn’t become dependent on it). I guess just when I think about it, I do it. That all could have combined with her not wanting to be awake and having a snotty cry. But she literally hasn’t coughed.

Post 5

Can anyone help? I have read all the posts and nothing I can find relates to me. I had a really bad cold and after the symptoms of the cold passed, I have had a persistent, dry cough followed by vomiting clear fluid. It happens at any time, sometimes up to six times a day.

Post 4

I have copd and a very bad nasal drip causing me to have excessive mucus in my throat and today I am throwing up bile. Should I go to the emergency?

Post 3

There is a condition called MALT. It stands for Mucosally Associated Lymphatic Tissue. Patches of tissue in the esophagus and stomach can become so irritated by repetitive exposures to endocrine system disruptive chemicals, from consumer products and environmental toxins, that they will dramatically react by excessively producing this thick "protective" mucosa.

In many cases you can eliminate the reaction by removing all toxins from your diet and environment. Some fragrances are major triggers, as are excitotoxins like MSG and aspartic acid, found in "flavors," seasoning mixes and meat tenderizers. Excito-toxins are also found in "broth" components of pet food. Stress can make the reaction worse.

Post 2

My dog has recently started vomiting mucus and the vet says he probably has indigestion from bolting his food. We recently got a puppy and there's a bit of jealousy going on there I think.

As we have a big yard it would have been easy to miss what was happening, so I've learned to keep a close eye on what he's up to after eating.

Having read this article I realise there are many other potential causes for dog vomiting. I would hate for him to be throwing up because he has a cold or chest infection and I didn't catch on.

Post 1

My friend's mother got pneumonia last year and was quite sick for a few weeks. Then one day she started throwing up green mucus and recovered pretty much instantly!

I'm happy for her of course, but a little tired of hearing the story of the miracle mucus. I would never have thought of this as a positive thing to be doing.

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