Spider Bites

From the Mayo Clinic patient handout
Spider bites are uncommon. Often, people mistake a skin infection or a bite by another insect as a spider bite.

Only a few spiders have fangs strong enough to pierce your skin and enough venom to cause a reaction. In the U.S., these include the black widow spider and the brown recluse spider. Even these types of spiders tend to bite only when threatened.

Spider bites are rarely lethal. Treating the site of the spider bite is generally all that’s necessary. In a few cases, symptoms may be severe and widespread enough to require antivenom treatment and hospitalization.

Symptoms
Typically, a spider bite looks like any other bug bite — a red, inflamed, sometimes itchy or painful bump on your skin — and may even go unnoticed. Harmless spider bites usually don’t produce other symptoms.

Symptoms of a black widow spider bite
Symptoms of a black widow spider bite depend on the area of the body bitten, how much venom was introduced and how sensitive you are to the venom. The venom can travel through your bloodstream and affect your nervous system, causing varying degrees of pain. Typical signs and symptoms include:

Mild stinging sensation when bitten (or no pain at all)
Slight swelling around one or two small bite marks
Dull, numbing pain progressing from the bite site to your abdomen and back (usually within an hour of being bitten)
Severe cramping or rigidity in your abdominal muscles
Other systemic signs and symptoms — ones that affect the whole body — that sometimes occur include:

Generalized, severe pain in your muscles and joints, abdomen or back
Nausea and vomiting
Dizziness
Profuse sweating
Tremors
Restlessness and anxiety
Increased blood pressure
Fever
Difficulty breathing
Facial swelling
Rash
Pain usually persists for the first eight to 12 hours. Signs and symptoms diminish and go away after several days, although you may still feel weak and experience residual spasms and restlessness for next few weeks or months.

Symptoms of a brown recluse spider bite
Usual signs and symptoms of a brown recluse spider bite include:

Mild burning or stinging sensation when bitten (or no pain at all)
Redness and slight swelling around two small bite marks
Increasing pain over the next two to eight hours, which may become severe
Over the course of several days, other less common signs and symptoms may appear:

Formation of a dusky red or blue (blood-filled) blister at the bite site, which then ruptures and sloughs off to leave a deep, enlarging ulcer (necrosis).
General feeling of illness
Nausea and vomiting
Fever
Body aches
When to see a doctor
A bug bite isn’t usually a reason to see your doctor, especially since it’s often hard to determine if the bite was from a spider and what kind of spider. But if you believe you’ve been bitten by a black widow or brown recluse spider, or you start to experience severe pain or cramping in your abdomen or back after a spider bite, see your doctor promptly…….