Almost every one will tear when cut onions. Because the onion contains a certain kind of elements which can stimulate our lacrimal gland. Then we will tear.
However, some people may react more seriously, others may just have the feeling of tearing. It depends on the intensity. If you were the kind of people who is highly sensitive of onion, you'd better stay away from onion.
Yes, it is nomal. The reason is that when onions are sliced, cells inside are broken, leading a kind of enzyme called alliinase to break down amino acid sulfoxides and generate sulfenic acids.Rapidly a volatile gas known as the onion lachrymatory diffuses through the air and reaches the eye, where it activates sensory neurons, creating a stinging sensation.Tear glands produce tears to dilute and flush out the irritant. However,Cutting onions under running water or submerged in a basin of water helps to avoid this kind of eye irritation.
Well, yes, it is normal to feel sensitive for your eyes when you cut onions. And in most cases, your eyes will tear. But you do not need to worry about it, and that can be ok. First, you should know that there are kinds of objects which have the irritant function in the onions. And then when you cut them, it will irritate your tear system and make you just like cry. To treat it, you can breathe through mouth while cutting onions and the mouth is open. Maybe you can have a try.