Although extremely painful and temporarily debilitating, fatalities from untreated widow bites are uncommon. During the period between 1926 to 1943, mortality ranged from 4 percent to 5 percent, but current medical treatments have reduced this to a much smaller incidence. Death usually results from respiratory paralysis. Prompt medical treatment can greatly reduce the danger from widow bites and has reduced fatalities to extremely low rates in recent years. Because of the possible severity of black widow bites, immediate medical attention is important.
Physicians can intravenously inject calcium gluconate to counteract most effects of the toxin.
The injection helps bolster levels of calcium salts that are depressed by the effects of the bite. A black widow antiserum also is available, although effects usually are less dramatic than the calcium gluconate treatment. First aid prior to the physician visit involves treating the bite site with antiseptics to prevent infections and trying to keep the patient quiet and warm. Because the toxin moves quickly in the body, attempting to suck out the poison is ineffective. Widow spiders are not aggressive and bites can be infrequent even when large numbers occur.