Why Do Onions Make You Cry? How to Cut Onions Without Tears

Whether you’re making a sandwich or cooking dinner, there’s a good chance you’ll be chopping onions for extra flavor. But why do onions make you cry—and how can you cut them without tears? Here are a few tips, plus the truth about whether leftover onions are safe to eat.

Why Do Onions Make You Cry?

When you cut an onion, you damage its cells. That starts a chemical reaction that releases a volatile compound called lachrymatory factor. It travels through the air and irritates your eyes, which respond by producing tears.

How to Cut Onions Without Crying

There are a few simple things you can try to reduce the tears:

• Use a sharp knife. A sharp blade cuts cleanly through the onion instead of crushing it.
• Chill the onion before cutting. Putting it in the refrigerator for about 30 minutes may slow the reaction that produces the eye-irritating compound. 
• Keep the root end intact until the end. Cut the onion in half from stem to root, then slice and dice each half without cutting through the root until you’re finished.
• Follow a steady cutting technique. See how to cut an onion in four easy steps.

Are Leftover Onions Poisonous?

No. A cut onion does not become poisonous simply because it has been cut or stored for later. Like other cut produce, though, it should be handled cleanly and refrigerated in a covered container. 

Wash your hands before preparing food, and use a clean knife and cutting board. Keep cut onions away from raw meat and poultry and their juices. If cut onions have been left at room temperature for more than two hours—or more than one hour when it’s hotter than 90°F—discard them. 

There’s a persistent myth that cut onions act like “bacteria magnets” and become dangerous to eat. They don’t attract germs in that way. As with other foods, safe handling and proper storage are what matter.

Enjoy your onions—and keep a sharp knife handy!