Science Questions

Why do my eyes water when I choke on food?

Sun, 8th Mar 2009

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Hazel asked:

Why, when I choke on food, do my eyes water?




Chris - The reason for that is because you have various reflexes that are designed to protect your airway. There's a nerve supply, the internal laryngeal nerve which is sensitive to everything touching your epiglottis inwards and down into your airway. You need to defend your airway very carefully because if anything goes in there it could threaten your ability to breathe. There's a very profound choking reflex and that triggers a cough. It also triggers various secretions to happen, the idea being that it will lubricate your mouth and anything that's stuck will get free. At the same time the same secretery, motor system also make your eyes water a bit. It makes tears come to your eyes and also what you're doing when you're coughing and choking you're blowing air up your tear duct. Normally the tears that you've got in your eyes drain down little punctum which is a little plug hole in your lower eyelid towards the middle. They go down towards the naso-lacrymal duct and tip into your nose. If you raise the pressure in your nose by coughing, sneezing, blowing your nose the pressure is reversed. It pushes the tears back up your tear duct and into your eye. There's two things going on. One you increase the secretions and two you probably jettison some tears back into your eyes.


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Hazel asked the Naked Scientists: Hello Chris and your team Can you explain why, when I choked on a piece of food just now , my eyes began to water? Hazel What do you think? Hazel, Mon, 9th Mar 2009

Coughing or sneezing clears the throat and nose of irritants, while tears clear the eyes.
Chemistry4me, Tue, 10th Mar 2009

But in this instance the object  or expectorant was caught I her throat not her eyes... I believe that there is a certain amount of pressure at the point air becomes short and th face and eyes strain an are squeezed in an attempt to remove object I think that loss of air etc..may trigger the tear glands pain and instinctual straining for air.....

Then again I am n expert. Karen W., Tue, 10th Mar 2009

Yes, I think you might be correct. I don't know what I was thinking last time.

Chemistry4me, Tue, 10th Mar 2009

The coughing itself isn't the cause of the eyes tearing up. Easily proven: If I let some saliva go back to the very edge of my throat my eyes immediately water up. I've done this before just to show people how to tear up on demand. So that throws the coughing theory right out the window. Matt McFarland, Mon, 24th Oct 2011

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