The first signs of a black widow spider bite are usually a pinprick sensation, minor swelling, redness and a target-shaped sore, Medline Plus explains. Within 15 minutes to an hour of getting the bite ...

The bite is usually flat, though it may develop a small blister ... spider bites usually don’t have a red center unless the venom is very mild. This is because the venom damages tiny blood ...

Black widow spider bites usually involve two puncture wounds and may cause a blister. Their venom contains ... Bruises result from broken blood vessels brought on by trauma to the body.