A spider bite rash typically develops shortly after a spider bite, and is an allergic reaction to the venom, causing swelling and itching. The most common treatment for a rash from a non-poisonous spider is to wash the area, place ice on the rash, and apply a topical steroid cream or take an oral antihistamine to control the allergic reaction and itching. Any signs of nausea, fever, or disorientation should be discussed with a doctor. If the spider is poisonous, the bite needs to be seen immediately by a doctor and while waiting for treatment, the rash should be iced and elevated.
Often the victim of a spider bite does not even know he has been bitten until the spider bite rash appears, and once the rash is observed it is best to wash the area with antibacterial soap or an alcohol wipe to prevent the wound from becoming infected. The wound should then be cooled with ice cubes or a cold compress for about 20 minutes to reduce the intensity of the itching and area of the spider bite rash, as well as abate the irritation. If the spider bite rash is bothersome, a topical steroid cream is very effective at controlling the allergic reaction and itching at the site of the bite. The lotion should be applied early and administered as directed until the bite rash disappears. An oral antihistamine can be used instead of a cream to control the allergic reaction and itch but unless directed by a doctor, an oral antihistamine and topical cream should not be used together.
It can be difficult to distinguish spider bites from other insect bites. Spider bites are typically painful and there is usually only one bite, or if there are multiple bites, they are usually in a line. A spider bite is initially round, flat, and itchy, and then a red, swollen, and very itchy rash develops. Sometimes one or two small dots are located in the center of the rash where the punctures occurred.
If the biting spider is observed, identifying the type of spider is necessary to determine if the spider is poisonous. A poisonous spider bite requires immediate medical attention, especially when the victim is a child, elderly person, or someone with a heart condition. Severe reactions to poisonous spider bites are fever, vomiting, headache, and abdominal or joint pain. If any of these symptoms are observed in conjunction with a suspected spider bite, it is prudent to see a doctor.