Your stomach produces mucus which acts as a barrier, protecting the stomach wall from digestive enzymes and acid. Some of this mucus can appear in vomit.

Mucus in your vomit may also come from your respiratory system, in the form of postnasal drip.

Keep reading to learn more about what causes mucus in vomit and when it might be a cause for concern.

It’s likely that you’ll see mucus in your vomit if you throw up when experiencing postnasal drip.

The glands in your nose and throat produce mucus that you commonly swallow without noticing. If you start to produce more mucus than usual, it can drain down the back of your throat. This drainage is called postnasal drip.

Postnasal drip may be caused by:

Postnasal drip and pregnancy

Nasal congestion is not unusual during pregnancy. Pregnancy hormones can dry out the lining of your nose, resulting in inflammation and swelling. The resulting stuffiness can make you feel like you have a cold.

Morning sickness (nausea and vomiting) occurs in 70 to 80 percent of all pregnancies. Experiencing both nasal congestion and morning sickness could explain seeing mucus in your vomit.

If your nausea and vomiting are so severe that it’s preventing you from getting proper nutrition and hydration, it’s important to visit your doctor.

Postnasal drip and children

When young children are congested, they’re often not good at blowing their nose or coughing up mucus. That means they’re swallowing a lot of the mucus.

This could cause an upset stomach and vomiting, or they could vomit after an intense coughing episode. In both instances, it’s likely there will be mucus in their vomit.

One reason we cough is to expel mucus from our lungs. Sometimes the coughing is so intense that it induces vomiting. This vomit will often contain mucus.

This severe type of coughing can be caused by:

Intense coughing that results in vomiting isn’t usually a medical emergency. Seek immediate treatment, however, if it’s accompanied by:

  • difficulty breathing
  • rapid breathing
  • coughing up blood
  • face, lips, or tongue turn blue
  • symptoms of dehydration

If your vomit is clear, it’s typically the indication that other than secretions, there’s nothing left in your stomach to throw up.

It could also indicate that you’ve recently had a large amount of water. If you drink too much water in a short period of time, your stomach can become distended, forcing you to vomit.

Clear vomit is typically not a medical concern unless:

  • you’re unable to keep liquids down for a prolonged period of time
  • your vomit begins to show signs of blood
  • you show signs of dehydration, such as dizziness
  • you have difficulty breathing
  • you experience chest pain
  • you have severe stomach discomfort
  • you develop a high fever

Mucus in your vomit could be from the protective lining in your stomach or from sinus drainage. In most cases, this is not a cause for concern unless it’s accompanied by other symptoms, such as:

Mucus in vomit is also not unusual or a cause of concern for pregnant women and small children.