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.
Dry the onion skins. After the onions are harvested, spread them out in a ventilated area so that the skins can harden. Do not remove the leaves. Allow the onions to cure for two to four weeks. Dry the onions in an area away from sunlight and humidity. Sunlight can taint the taste of the onions and make them bitter.