Why do onions make us cry?

When your child asks, here's how to answer — in their words, and in yours.

For your child

Onions make you cry because when you cut them, they release a special puff of air that tickles your eyes. Your eyes then try to wash that tickle away with tears, like when you get dust in them!

Heads up

The answer simplifies the complex chemical reaction that produces the irritating gas in onions. The specific enzymes and compounds involved are omitted, as is the formation of sulfuric acid in the eyes.

For you

When an onion is cut, its cells are broken, releasing chemicals that mix to form a sulfur-containing gas. This gas rises and reacts with the water in your eyes, forming a mild acid that irritates them, leading to tear production as a protective response.

They might ask next

Do all vegetables make us cry?
What happens if you don't cry when cutting onions?
Can other things make my eyes water like that?

Whyzard answers your child's own questions — out loud, in words they'll understand.