Bodily Oddities

Gag reflex

Also called: Pharyngeal reflex

Touch the back of the tongue or the soft palate and the throat clamps shut. It keeps things out of the airway. About a third of healthy people have no gag reflex at all, and that is normal.

Mouth and throat Nerves Reflex

How common

Present in about 2 of 3 people, absent in 37% in one study Absence in a healthy person is not a sign of disease.

Does this happen to you?

How it works

The gag reflex is a guard on the airway. Its sensors are in the back of the tongue, the soft palate, the tonsil area, and the back wall of the throat. Touch any of them and the throat squeezes shut and the soft palate lifts. This throws an object away from the windpipe1.

Two cranial nerves run it. The glossopharyngeal nerve carries the touch signal to the brainstem2. The vagus nerve carries the order back to the throat muscles3. The loop is fast and does not involve thinking. Doctors test it to check that this part of the brainstem is working1.

The reflex is not the same as the swallowing reflex. Food that is chewed and moved back on purpose does not trigger it. An object placed at the back of the mouth can trigger it1.

How common it is

A surprising number of healthy people have a weak gag reflex or none at all. In a 1995 study by Davies and colleagues, 37% of healthy adults did not gag when the back of the throat was touched1. This is a normal variation and it does not mean the airway is unprotected. Coughing and swallowing do most of the real work.

Other people have a very sensitive reflex. For them, dental work, throat swabs, and even brushing the back teeth are difficult. A bad past experience can make it worse1.

Is it a problem?

No. A weak or absent gag reflex in an otherwise healthy person is a normal variation, not a sign of nerve damage1. A strong reflex is not a problem either, though it can make dental visits and throat swabs harder.

See a doctor if a gag reflex that used to work disappears suddenly, especially alongside:

  • trouble swallowing,
  • a change in voice,
  • weakness on one side of the face.

A stroke or nerve injury can cause that pattern123.

History and culture

The reflex can be trained down. Sword swallowers spend months or years learning to keep their throat relaxed while a blade passes the exact points that trigger the gag45. Some dentists teach patients to press a thumb into the palm during treatment. There is little good evidence for this trick1.

Sources and further material

  1. Wikipedia Pharyngeal reflex Davies and colleagues, 1995, found the reflex absent in 37% of healthy adults.
  2. Wikipedia Glossopharyngeal nerve The nerve that senses the touch.
  3. Wikipedia Vagus nerve The nerve that drives the throat to contract.
  4. Wikipedia Sword swallowing Performers who train the reflex away.
  5. NCBI Sword swallowing and its side effects Witcombe B, Meyer D, 2006 BMJ. Most performers needed daily practice over months or years. They desensitise the gag reflex.

Updated , first published .

Missing something your body does? Tell me about it.

Mouth Involuntary

Tonsil stones

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