Serious spider bites are a rare occurrence in the United States. Still, being able to recognize the two dangerous species as well as the symptoms of their bites is important. Spider bites can lead to anything from mild localized swelling to death.
In the United States, the black widow and the brown recluse are the major threats, though neither is as dangerous as the Sydney funnel web spider in Australia. Identification of the spider is key to understanding the side effects of its bite.
Side effects from most spider bites are generally very mild. The bite site might become red, inflamed and itch. The amount of pain it brings depends on how much venom the spider injected and the species of spider.
The black widow is perhaps the most well-known spider in the world. Its bite can cause swelling, pain, itching, rigid muscles, abdominal pain, nausea and can be fatal in extreme cases. The widow family also includes the red widow, the brown widow, the red back spider and the southern black widow. All have similar side effects in varying degrees.
The brown recluse is a bit smaller than the black widow and has a very different type of venom. Its bite causes necrosis (tissue death) at the site that has a tendency to spread. This can lead to horrific wounds that can lead to amputation in extreme cases. Common side effects are pain, swelling, necrosis and a wound that grows and does not heal on its own.
Other spiders of the world can be particularly deadly. The Sydney funnel web spider of Australia and the Brazilian wandering spider can kill anyone who does not get immediate medical treatment after being bitten.