Spider bites: Bites from spiders. These are usually irritating, but not poisonous. Localized reddening and swelling are common and pass within a few days. A few spiders are poisonous, in the US notably the black widow and brown recluse (brown fiddler). Bites from these spiders require emergency treatment, especially for children.
However, most spiders do not pose a medical risk. Even spiders that can cause clinically significant bites cause very little mortality or severe morbidity. Scorpions are responsible for a far greater burden of illness and bee and wasp stings account for many more deaths than spider bites.