Major side effects of this drug include agranulocytosis and methemoglobinemia. Therefore, it is not recommended in young children. Data is neither consistent nor convincing on its efficacy. While Maynor et al. found that HBO within 48 hours of envenomation significantly reduced wound size, Hobbs et al. found no difference in wound size between controls and among those animals treated with either dapsone, HBO, or a combination of the two. Most common reported side effects of HBO include ear, sinus and pulmonary barotrauma and seizures from oxygen toxicity.
Surgery remains the final option for complicated, large, non-healing disfiguring cutaneous ulcers.
Clinical experience demonstrates that early wide excision is ineffective, unnecessary, expensive, risky and often more cosmetically disfiguring. If required, it should be done after the lesion is well established, usually within 2-8 weeks after the bite. After this period, skin grafts usually heal well. Interestingly, Rees et al. found reduced incidence of wound complications and objectionable scarring in those patients pretreated with dapsone and delayed wound excision compared to those patients undergoing early surgical intervention. Fortunately, the venom of the Loxosceles reclusa usually causes a trivial and painless lesion, which heals spontaneously with meticulous wound hygiene.