Many therapies have been used including hyperbaric oxygen, dapsone, antihistamines (e.g., cyproheptadine), antibiotics, dextran, glucocorticoids, vasodilators, heparin, nitroglycerin, electric shock, curettage, surgical excision, and antivenom. None of these treatments conclusively show benefit. Studies have shown surgical intervention is ineffective and may worsen outcome. Excision may delay wound healing, cause abscesses, and lead to objectionable scarring.Dapsone, an antibiotic, is commonly used in the United States and Brazil for the treatment of necrosis. There have been conflicting reports with some supporting its efficacy and others have suggested it should no longer be used routinely, if at all. Antivenom
Use of antivenom for severe spider bites may be indicated, especially in the case of neurotoxic venoms. Effective antivenoms exist for Latrodectus, Atrax, and Phoneutria venom. Antivenom in the United States is in intravenous form but is rarely used, as anaphylactic reaction to the antivenom has resulted in deaths. In Australia, antivenom in intramuscular form was once commonly used, but use has declined. In 2014 some doubt as to antivenom effectiveness has been raised. In South America an antivenom is available for Loxosceles bites, and it appears antivenom may be the most promising therapy for recluse bites. However, in experimental trials recluse antivenom is more effective  when given early, and patients often do not present for 24 or more hours after envenomation, possibly limiting the effect of such intervention. Epidemiology
Estimating the number of spider bites that occur is difficult as the spider involvement may not be confirmed or identified.
Several researchers recommend only evaluating verified bites: those that have an eyewitness to the bite, the spider is brought in, and identified by expert. With "suspected arachnidism" the diagnosis came without a spider positively identified. Africa
Several Latrodectus species (button spiders) live in Africa. South Africa also has six-eyed sand spiders (Hexophthalma species), whose bite may potentially cause skin necrosis. Physicians are advised that the diagnosis may be difficult without a spider. Australia
Bites by the redbacks (Latrodectus hasselti) number a few thousand yearly throughout the country. Antivenom use is frequent but declining. Children may have fewer complications from bites. Funnel web spider bites are few 30–40 per year and 10% requiring intervention. The Sydney funnel web and related species are only on the east coast of Australia. Europe
In Switzerland about ten to one hundred spider bites occur per one million people per year. During epidemics of latrodectism from the European black widow upwards of 150 bites a year were documented. North America
The American Association of Poison Control Centers reported that they received calls regarding nearly 10,000 spider bites in 1994. The spiders of most concern in North America are brown recluse spiders, with nearly 1,500 bites in 2013 and black widow spiders with 1,800 bites. The native habitat of brown recluse spiders is in the southern and central United States, as far north as Iowa. Encounters with brown recluse outside this native region are very rare and bites are thought to be suspect. A dozen major complications were reported in 2013.