Time. Most spider bites cause only a small local allergic reaction. If this is all it is some anitbiotic ointment a bandaid and time (1 to 2 days) and it should be fine. If it looks like it is getting infected ( increasing redness, pain or not improving) you should see your doctor. Only a small minority of spider bites cause infection or serious skin injury.
Spider. Seek medical care asap if you think a spider bit you & you have fever, severe pain (can be felt at bite site & possibly chest, back or abdomen); abdominal cramping /rigidness or ulceration of skin at site. Cleanse site with soap & water. Remove jewelry. Can use Benadryl for itching, Tylenol (acetaminophen) for pain and cool compresses.You may need a tetanus shot (if you don't know when your last shot was or it.