Though many people are afraid of spiders, they rarely bite people unless threatened. Most spider bites are harmless. Occasionally, spider bites can cause allergic reactions. And bites by the venomous black widow and brown recluse spiders can be very dangerous to people.
If you are bitten by a spider, you may see a reaction similar to that of a bee sting, including redness, pain and swelling at the site. To treat a spider bite:
References and abstracts from MEDLINE/PubMed (National Library of Medicine)