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 (toxin) to cause a dangerous reaction. Many 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 red or orange hourglass figure on its underside. It is about an inch 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.

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 a dark brown, violin-shaped spot on its head. It is about 1/2 inch long, including the legs. 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. There are over 1200 species of scorpions worldwide and over 40 species in the US. Only the bark scorpion has a sting that is dangerous unless you are allergic to scorpions. 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 similar to the symptoms of nonpoisonous spider bites or scorpion stings:

• minor pain or soreness around the wound
• mild swelling
• tiny red bite or sting 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 cramps starting in the muscles around the bite and then spreading to other muscles
• abdominal pain or cramps
• dizziness
• seizures
• fever and chills
• general weakness
• nausea and vomiting
• sleepiness
• increased saliva
• headache
• diarrhea
• profuse sweating
• eye sensitivity to light
• trouble breathing

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?

Your healthcare provider will examine you, ask about your symptoms, and ask if you saw the spider or scorpion. There are many things that can cause a reaction that looks like a spider bite or sting. Other causes of the rash or reaction need to be ruled out, such as:

• allergic reaction to something else
• anxiety or panic attack
• infection (viral or bacterial)
• blood vessel inflammation (vasculitis)
• ingrown hairs and other causes of skin abscesses

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:

• Wash your hands thoroughly with soap and warm water for at least 15 seconds before you touch the area.
• Wash the bite twice a day with mild soap and water unless your provider tells you to do something else.
• When you are cleaning the bite, look for signs of infection such as increased swelling, redness, red streaks going away from the wound towards your heart, and any drainage.
• Keep the area of the bite clean and dry.
• Put ice or cold, moist washcloths on the bite to keep the swelling down.
• Put a nonprescription hydrocortisone cream on the skin to reduce the itching.
• Take nonprescription antihistamines, such as Benadryl, Zyrtec, or Claritin.
• Take acetaminophen (Tylenol®) or over-the-counter anti-inflammatory medicine such as ibuprofen (Motrin®, Advil®) or naproxen (Aleve®, Naprosyn®) to help decrease pain.
• Watch for 24 hours for symptoms of a systemic reaction.
• Check with your healthcare provider to make sure that your tetanus shots are up to date.
• If you can, safely catch the spider or scorpion in a jar, 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).
• Put ice on the wound to slow absorption of the toxin.
• 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.

Some bites and stings, like a black widow bite, can cause symptoms that worsen for the first 24 hours. In this case, you may need to be observed in the hospital during that time.

Call 911 or have someone take you to the closest hospital emergency department right away if:

• You start to have trouble breathing, trouble swallowing, develop hives, feel very weak or light headed, or feel tightness in your throat.

Call your healthcare provider right away if:

• You start to have any signs or symptoms of infection. These include:
  • The skin is becoming redder or more painful.
  • You have red streaks from the abscess going toward your heart.
  • The wound area is very warm to touch.
  • You have pus or other fluid coming from the wound area.
  • You have a fever higher than 101.5°F (38.6°C) orally.
  • You have chills, nausea, vomiting, or muscle aches.
• Your symptoms are getting worse, not better.
• You have a question about whether your bite or sting needs to be treated.
• You have any symptoms that worry you.

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 more serious injury to 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. Bites that cause the skin to die in an area need to be followed up closely. In some cases, when large areas of skin are lost, skin grafts are needed to repair the wound.

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, rock piles, or dark corners of outdoor buildings.
• Spray insecticides in any area where black widow or brown recluse spiders are seen.
• 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 the most likely to get sick from spider bites and scorpion stings. You may need to help them take the precautions against bites and stings.