"It's a black widow!" Spider bites are quite common, but in most cases it's usually a bite of an aggressive house spider that is more likely the culprit. Whether you or your child should be seen by a physician, is usually an all too familiar dilemma. Good recognition of the venomous spiders such as black widows and brown recluses are important for each parent to know before sending your child (or yourself) to the doctor.

Brown Recluse and Black Widow spiders, are two of only four types of spiders (the others being Hobo spiders and Yellow Sac spiders) that are thought to be dangerous to humans. Tarantulas are another type of spider of common concern, but in most cases are usually harmless.

Brown Recluse Spiders

These are brown small spiders (about ½ inch in length) that are known for a violin shaped pattern on their head (that is why they are also known as "fiddleback spiders"). These spiders usually bite only when threatened (hence their name "recluse") and are commonly found in attics and usually hide in clothings. The bite of the Brown Recluse can cause pain and blistering usually after four to eight hours. The wound then may scab and cause sloughing of the skin. The main danger is the bite being so extensive that the skin may necrose, requiring skin grafting in the future. If severe, brown recluse spiders may also cause widespread reactions such as fevers, nausea, vomiting and muscle pains.

Treatment involves tetanus immunizations if overdue, cool compresses or ice packs and antibiotics for infections. Anti-venom is also available for severe cases. A medication known as dapsone has been shown to minimize inflammation and slow formation of necrotic lesions but its use is controversial among doctors.

Black Widow Spiders

These are long, slender black spiders known for their red or orange hourglass pattern located on their undersides. They are predominately found in the southern regions of America. Black Widow spiders can cause temporary numbness and tingling at the site of the bite. Systemic reactions include nausea and vomiting, sweating and abdominal pains. Muscle cramping may be significant. Rare side effects include low blood pressure, coma and death.

In addition to the similar treatment for Brown Recluse spiders (immunizations and ice packs), calcium gluconate may be used for severe reactions. Benzodiazepines may be used for muscular relaxation.Anti-venin therapy is used in severe, life-threatening cases.

Tarantulas

Tarantulas are hairy spiders most commonly seen in the southwest regions of America. In recent years their popularity as house pets have caused the number of Tarantula bites to rise. Their bites usually are not serious and can cause a mild sting and localized pain. Hairs expelled from the legs of the Tarantula may cause itching and form red papules on the skin. Severe allergic reactions are rare but can occur.

Treatment involves wound cleaning and tetanus immunization. Cool compresses may ease the pain. Topical steroid creams and anti-histamine medications will help with itching.

Reference: Goldman. Cecil's Textbook of Medicine.