Brown Recluse Spider Bite

Two images: One of a brown recluse spider. The other of a human arm showing redness and small wound caused by a brown recluse spider bite. Labels include: Brown recluse spider, Brown recluse spider bite

Most spiders are harmless to people. But there are 2 spiders in the U.S. that can cause harm: the black widow and the brown recluse.

Brown recluse spiders may be light or dark brown. They are ¼ inch to ¾ inch long, and have long, thin, legs. Some have a fiddle-shaped mark on their back. They are most often found in the South, West, and Midwest. They live in places such as closets, attics, basements, porches, barns, and woodpiles.

A brown recluse spider bite may be painless at first. Or it may burn slightly like a bee sting. A small red mark may form at the site. Then small blisters may appear. In 2 to 8 hours, the area may become painful, swollen, and itchy. Other symptoms can include a general feeling of discomfort (malaise), fever, joint pain, nausea, and vomiting. In most cases, the bite site heals on its own in a week. But in some cases, the skin at the bite site may break down. (For instance, the skin may turn black and sink down as the tissue below dies.) This can cause an open wound called an ulcer to form. It may take a few weeks to a few months to heal. In rare cases, a brown recluse spider bite leads to more serious problems. These can include muscle damage, kidney failure, problems with blood clotting, and coma.

The bite site will be cleaned. Medicines may be given to relieve pain, if needed. Antibiotics may also be given to treat infection. A tetanus shot may be given. If an ulcer forms, skin grafting may be needed later to repair severe damage to the skin. But most bites heal without scarring.

Home care

  • You may use acetaminophen or ibuprofen to relieve pain, unless another pain medicine was prescribed. Talk with your healthcare provider before using these medicines if you have chronic liver or kidney disease or ever had a stomach ulcer or GI bleeding.

  • If you were prescribed antibiotics, take them exactly as directed. Also be sure to complete the medicines.

  • Care for the bite site as directed by your healthcare provider. This may involve cleaning the wound at least once a day with soap and water.

  • To help ease pain and swelling, apply cold packs to the bite site as directed. You can use a cool wet washcloth. Or you can make a cold pack by filling a plastic bag that seals at the top with ice cubes and wrapping it with a thin towel. Don't apply ice directly on the skin.

  • If you were bitten on the arm or leg, keep the body part raised (elevated). Swelling may worsen in the down position.

  • Check the bite site daily for signs of infection (see below).

Follow-up care

Follow up with your healthcare provider, or as advised.

When to get medical advice

Call your healthcare provider right away if any of these occur:

  • Fever of 100.4°F (38°C) or higher, or as directed by your provider

  • Pain worsens and is not relieved with medicine

  • Signs of infection at the bite site such as increased redness or streaking, swelling, or foul-smelling drainage

  • Bite site becomes black or blue

  • Bite site won’t heal or grows larger

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