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.
The onion allergy reacts very quickly. It can start within a minute after eating onions. The reaction can be very severe and life threatening. But with onion intolerance, it may take up to a day for the symptoms to appear and the reaction is mild . Some people canât tolerate the sulphur and chemical that onion has.