Are all spider bites or scorpion stings dangerous?

Most spiders and scorpions have too little poison to cause a dangerous reaction. Only a few cause dangerous bites. Spiders in the US whose bites or stings can be serious are:

• A black widow spider, which is a shiny, black spider with a fat body and a red or orange hourglass figure on its underside. It is about an inch (2.54 cm) long, including the legs. It is found in most parts of the US. It is often found in woodpiles, sheds, fruit and vegetable gardens, garages, and outdoor toilets. The bite of the female spider is more serious than the bite of a male spider.
• The brown recluse spider, which is also called a brown, fiddleback, or violin spider. It has long brown legs and a dark brown, violin-shaped spot on its head. It is about 1/2 inch (1.3 cm) long, including the legs. This spider is most active at night and is found indoors in cardboard boxes, garages, basements, attics, and closets in the midwestern and southern parts of the US. It may also be found outdoors in rock piles, leaves, or woodpiles.
• The hobo spider, which is brown with grey markings. Found in the northwestern US, it is seen more often in midsummer and fall. The hobo spider is found in dark, moist places such as basements, crawl spaces, and woodpiles.

Scorpions are related to spiders and have a long body, 8 legs, and a tail that curls up when they are about to sting. Most scorpions in the US are not poisonous. The most common poisonous scorpion is the bark scorpion. The bark scorpion is pale gold or tan, and usually less than 3 inches (7.6 cm) long. It can be found in wood piles, trees, walls and in rocky areas in the southwestern US. Scorpions are most active at night.

What are the symptoms?

The symptoms of any bite or sting start within a few hours to a day after the bite. Symptoms include:

• Minor pain, redness, or swelling around a red bite or sting mark
• Numbness or tingling

Symptoms of a more serious reaction or a poisonous bite or sting may include:

• Fever and chills
• Severe pain in the muscles around the site of the bite
• Lightheadedness or dizziness
• Anxiety or restlessness
• Weakness
• Nausea and vomiting
• Headache

If symptoms worsen or new symptoms develop within 10 minutes to several hours after a bite or sting, see your healthcare provider or go to the emergency room right away.

A severe allergic reaction usually happens within minutes of the bite or sting and it can affect your whole body. The symptoms may include:

• Itching of the mouth and throat
• Severe swelling of the lips, tongue, or throat
• Wheezing or trouble breathing
• Nausea, cramping, diarrhea, or vomiting
• Hives
• Dizziness
• Loss of consciousness

If you have symptoms of a severe allergic reaction, call 911.

How is it diagnosed?

Your healthcare provider will ask about your symptoms and medical history and examine you.

How should I treat a spider bite or scorpion sting?

If you have a mild reaction to a bite or sting:

• Wash the area that was stung or bitten.
• Make a paste of 3 teaspoons baking soda and 1 teaspoon water put it on the area of the bite or sting.
• Put a cold, moist cloth or a bag of ice covered in a towel on the area 3 to 4 times a day for 15 to 20 minutes. Never put ice directly on your skin. This could cause frostbite.
• If other treatments don’t help with the itching, you can try hydrocortisone cream or calamine lotion on the area. You can also try antihistamine pills, such as Benadryl, for itching. Read the label and take as directed. Antihistamines may make you drowsy. Do not drive or operate machinery or equipment while you are taking this medicine. Do not use antihistamine lotions while taking antihistamine pills.
• If the bite is painful, take nonprescription pain medicine, such as acetaminophen, ibuprofen, or naproxen. Read the label and take as directed. Unless recommended by your healthcare provider, you should not take these medicines for more than 10 days.
  • Nonsteroidal anti-inflammatory medicines (NSAIDs), such as ibuprofen, naproxen, and aspirin, may cause stomach bleeding and other problems. These risks increase with age.
  • Acetaminophen may cause liver damage or other problems. Unless recommended by your provider, don’t take more than 3000 milligrams (mg) in 24 hours. To make sure you don’t take too much, check other medicines you take to see if they also contain acetaminophen. Ask your provider if you need to avoid drinking alcohol while taking this medicine.
• Rest the bitten area on a pillow higher than your heart as much as possible for the first 1 to 2 days. This can help prevent or reduce swelling.

If you have more serious symptoms, put a cloth-covered ice pack on the area. If the scorpion or spider may be poisonous, seek care right away. If it can be done safely, take the spider or scorpion in a jar or sealed plastic bag to the emergency room, so it can be identified. Some bites and stings, like a black widow bite, can cause symptoms that worsen for the first 24 hours.

Medical care for a bite or sting may include:

• A tetanus booster shot if the skin is broken and infection develops
• Pain medicine
• Medicine to stop an allergic reaction
• Wound care for the bite
• Antibiotics to treat infection
• Antivenom to stop the effects of the spider or scorpion poison

How can I help prevent spider bites or scorpion stings?

To avoid getting bitten or stung by a poisonous spider or scorpion:

• Use traps indoors. Traps are usually sticky surfaces that trap the spiders or scorpions. They are the safest and most effective way to control spiders or scorpions inside your home. If you have a lot of spiders or scorpions, contact a pest control service.
• Wear gloves, long pants, heavy clothing, and socks stretched over your pants when you are around wood piles, rock piles, or dark corners of outdoor buildings.
• Spray insecticides in any area where poisonous spiders are seen.
• Wear gloves when you are gardening or working in the basement or attic.
• Don’t leave your clothes on the floor.
• Inspect and shake clothing and shoes before putting them on.
• Pull back and check bedding before going to bed.
• Inspect outdoor toilets carefully before using them. Avoid sitting on outdoor toilet seats.
• Don’t go barefoot or wear open sandals around areas where spiders and scorpions are commonly found.
• Discourage children from playing near areas where spiders and scorpions are commonly found.

It is also important to prevent tetanus infection. The skin broken by a bite or sting could get infected with tetanus bacteria. You can prevent this by keeping up to date with tetanus shots. After childhood, you need a tetanus booster shot every 10 years, even if you never have a dirty cut or puncture wound.