1 Pain that does not diminish with rest, and pain that may be worse at night than during the day. 2  Back pain along with constitutional symptoms, such as loss of appetite, unplanned weight loss, nausea, vomiting, or fever, chills or shakes.
Unstable chemicals. Onions produce the chemical irritant known as syn-propanethial-S-oxide. It stimulates the eyes' lachrymal glands so they release tears. Scientists used to blame the enzyme allinase for the instability of substances in a cut onion.
Health Benefits of Onions. Here are some of the common health benefits of onions. 1  Better Oral Health â This may seem odd since onions can cause bad breath, but chewing raw onion is known to improve the strength of the teeth and fight off bacteria which can cause tooth decay.