Why do garlic and onions make you cry?
Show answer & explanation
Answer: Sulfur gas irritates eyes
Spicy oils burn eyes — Wrong. They're not spicy oils. Cutting releases enzymes that produce sulfuric acid gas, which irritates eyes and causes defensive tearing.
Sulfur gas irritates eyes ✓ — Correct! Onions and garlic store sulfur compounds. Cutting breaks cells, releasing enzymes (alliinase) that convert these compounds into syn-propanethial-S-oxide—a volatile sulfur gas. This reaches your eyes and reacts with water to form sulfuric acid, irritating nerves. Your eyes tear up defensively! Defense against herbivores.
Allergic reaction to plants — Wrong. It's not an allergy—it's a chemical defense. Everyone's eyes tear from the sulfur gas produced when cutting onions/garlic.