Spider Bites and Scorpion Stings

Is a spider bite or scorpion sting dangerous?

There are thousands of types of spiders. All spider bites are poisonous, but usually they are not dangerous to people. Most spiders have too little poison or they are too small to be able to break your skin with their fangs. Only a few spiders cause dangerous bites. Because most spider bites are not dangerous, the bites usually do not need medical treatment.

There are about 40 different types of scorpions in the southwestern part of the US. Just 1 of these types has a sting that can be lethal.

Spiders and scorpions in the US whose bites or stings can be serious are the:

• black widow spider
• brown recluse spider
• hobo spider
• bark scorpion.

What is a black widow spider?

A black widow spider is a shiny, black spider with a fat body and a distinctive red or orange hourglass figure on its underside. 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.

What is a brown recluse spider?

The brown recluse spider is also called a brown, fiddleback, or violin spider. It has long brown legs and slightly darker brown markings on its head that look a little like a violin. This spider is most active at night and is found in cracks, crevices, basements, attics, and dark closets of houses in the Midwestern and southern parts of the US. It may also be found outdoors in piles of rock, leaves, or wood.

What is the hobo spider?

The hobo spider is brown with grey markings. Found in the northwestern US, it is seen more often in midsummer and fall. The hobo spider likes dark, moist places such as basements, crawl spaces, and woodpiles.

What is a scorpion?

Scorpions are related to spiders. They have a long body and a tail that curls up when they are about to sting. The bark scorpion can be found in junk and wood piles and in rocky areas in the southwestern US.

What are the symptoms of a spider bite or scorpion sting?

There are 3 main types of reactions to spider bites or scorpion stings:

• local reaction to the venom (affecting just the area of the bite), causing redness and other mild symptoms
• local allergic reaction causing allergic symptoms in the area of the bite, such as itching
• systemic allergic reaction (affecting the whole body and potentially life-threatening), causing throat swelling and trouble breathing.

At first the symptoms of a poisonous spider bite or scorpion sting are the same as a minor spider bite or scorpion sting, that is:

• minor pain or soreness around the wound
• swelling
• tiny red bite mark
• tenderness
• redness of the skin
• numbness
• tingling.

Symptoms of a more serious spider bite or scorpion sting causing a systemic allergic reaction may include:

• severe pain at the site of the bite
• itching of the nose, throat, and mouth
• wheezing or trouble breathing
• muscle spasms
• abdominal pain or cramps
• dizziness
• seizures
• fever and chills
• general weakness
• nausea and vomiting
• sleepiness
• increased saliva.

Symptoms of a minor spider bite usually go away in 2 to 3 days. 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.

How is it diagnosed?

80% of all suspected spider bites or scorpion stings are caused by other things. To be sure that a rash or bite is caused by a spider or scorpion, 3 things need to happen:

• You must see the spider or scorpion biting or stinging the person.
• It must be caught and identified.
• Other causes of the rash or reaction need to be ruled out, such as:
  • allergic reaction to something else
  • anxiety or panic attack
  • other infection (viral or bacterial)
  • blood vessel inflammation (vasculitis).

How should I treat a spider bite or scorpion sting?

Self care for a minor bite or string that causes just a local reaction is as follows:

• Clean the area with mild soap and water.
• Apply ice to reduce the swelling.
• Put cold, moist washcloths on the bite to keep the swelling down.
• Put a nonprescription hydrocortisone cream on the skin to reduce the itching.
• Watch for 24 hours for symptoms of a systemic reaction.
• Get a tetanus shot if you have not had one for at least 5 years.
• If you can, safely catch the spider or scorpion, in case you need to find out what kind of spider or scorpion it is.

To care for a more serious bite:

• At first treat it like a local reaction as described above.
• Put a large soft bandage over the bite.
• Try not to move the area where you were bitten (keep it resting).
• If you are having any of the more serious symptoms, contact your healthcare provider or go to the nearest emergency room right away. Try to take the spider or scorpion with you for identification.

What will the healthcare provider or the emergency room doctor do?

• You may get a tetanus booster shot if the skin is broken and infection develops.
• You may be given a nonprescription pain reliever, such as aspirin or acetaminophen.
• You may be given steroid medicine in a vein (IV).
• You may be given a shot of calcium gluconate to help with severe muscle pain.

What is antivenom?

Antivenom is a type of medicine given to stop the effects of the spider or scorpion poison. It is formed from horse blood. Most venom is absorbed completely after only 30 minutes, so antivenom must be given as soon as possible. It is given only to people who are having severe symptoms. One in 10 patients given antivenom have a severe reaction to it.

How long will the effects of a spider bite or scorpion sting last?

Local reactions last 7 to 10 days. They are usually minor and go away without complications in a few days.

More severe bites can cause more pain, fever, and muscle aches for a few days and marked changes in your skin. Some bites may cause blisters to form within the first 15 to 36 hours. Within a day after they form, the blisters open and ooze, causing a sore. The venom may cause the skin and underlying tissue around the bite to die. The skin usually turns dark and a small hole may develop in the skin. This requires different treatment than a simple bite.

How can I 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 serious infestation, you should seek the advice of a pest control service to learn if there is a safe yet effective pesticide that will kill the spiders or scorpions.
• Wear gloves, long pants, heavy clothing, and socks stretched over your pants when you are around wood piles or sheds.
• Wear gloves when you are gardening or working in the basement or attic.
• Inspect and shake outdoor clothing and shoes before putting them on.
• Check your shoes before you put them on.
• Pull back and check the bed linens before going to bed.
• Inspect outdoor toilets carefully before using them.
• Do not go barefoot or wear open sandals around areas where scorpions may be.
• Discourage children from playing near spider and scorpion-infested areas.

Young children and the elderly are most susceptible to the effects of spider bites and scorpion stings. You may need to help them take the above precautions.

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Published by RelayHealth.
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