When a spider bites, it may leave two marks on the skin. Some spider bites can produce severe symptoms, but very few are life threatening, and most spiders cannot bite humans.

In this article, find out how to recognize the symptoms of different spider bites and learn about some spiders that can bite humans.

There are over 3,500 spiders in the United States, but most are not dangerous. Only two species raise significant medical concerns: the widow and the recluse.

Most spiders bite, but their fangs are too small or weak to puncture human skin. Many spiders have weak or prey-specific toxins that are unlikely to affect humans. If they do bite, they may leave itchy, red wounds that heal within a week or so.

However, some spiders can bite through human skin and insert powerful toxins. Bites by these spiders are rarely fatal but can cause health complications, such as tissue death and painful muscle spasms.

Read on to learn:

  • what spider bites look like
  • what spider varieties leave certain bites
  • how to treat spider bites

Identifying a spider bite is easier if you saw the spider that bit you, but you may not notice the wound until hours later.

Look for things like:

  • swelling
  • a red welt
  • skin damage
  • any troubling symptoms that accompany the bite

Other possible symptoms that may accompany a spider bite include:

Spider bites can take longer to heal than other insect bites and may affect skin tissues. Keeping the bite clean can reduce the risk of infection.

In some cases, you can treat spider bites at home. For nonvenomous spider bites, follow these steps:

  • Apply an ice pack on and off the bite for 10 minutes at a time. Always wrap ice or an ice pack in a cloth.
  • Elevate the area to reduce swelling.
  • Take an antihistamine, such as diphenhydramine (Benadryl), to help with itching.
  • Clean the area with soap and water to prevent infection.
  • Apply antibiotic ointment to the area if blisters develop.

Seek medical attention if you’re showing symptoms of a spider bite or if the symptoms don’t go away over time.

Always seek medical attention if you suspect one of the following species has bitten you:

  • brown recluse
  • black widow
  • hobo spider
  • tarantula
  • Brazilian wandering spider

Learn where these spiders hide and what they look like below.

The brown recluse belongs to the Loxosceles or recluse family of spiders. Brown spiders, like the brown recluse, have a body around one-third of an inch long.

Brown recluse spiders are not usually aggressive but will bite if trapped against a person’s skin. They typically hide in dark, secluded spaces. It’s also called the violin spider because of the dark marking on its back.

The brown recluse is usually found in areas such as:

  • Missouri
  • Tennessee
  • Kansas
  • Arkansas
  • Louisiana
  • Oklahoma
  • Eastern Texas

The initial brown recluse bite may be painless, but within 2–8 hours, it’ll begin to itch, hurt, and turn red. A red or purple ring resembling a target or bull’s-eye will develop around the bite.

The bite can blister and grow progressively worse without treatment to the point where it may kill surrounding tissue and cause fever, chills, and headache.

On rare occasions, it can cause:

There’s no antidote for a brown recluse bite, but keeping the area clean can encourage faster healing.

Your doctor will examine the bite and prescribe antibiotics. People who experience tissue death may need surgery and time in the hospital.

How do you treat a brown recluse spider bite?

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Image credit: spotwin/Istock

The black widow spider is of the Latrodectus (widow) family of spiders. It is shiny and black with a distinct, reddish, hourglass-shaped mark on its belly. The body is around half an inch long.

Found mostly in the warm Southern and Western United States, the black widow stays in secluded spaces such as:

  • piles of fallen leaves
  • woodpiles
  • boxes in the attic

Only the female black widow is toxic. Black widow bites can feel like a small pinprick or nothing at all, but your skin’s reaction will be immediate. You’ll be able to see the two puncture marks on your skin.

Within an hour, you may start to notice:

  • muscle cramping
  • pain and burning at the puncture site
  • headache
  • high blood pressure
  • increased saliva and sweating
  • nausea and vomiting
  • numbness
  • restlessness

Prompt treatment is essential, especially in children and older adults. A doctor may prescribe an antivenom.

What happens if a black widow spider bites you?

Hobo spiders are common in the Pacific Northwest. Their body measures around half to three-quarters of an inch long. They sit up high on long legs and run fast.

Hobo spiders can bite when provoked.

Take care when cleaning:

  • behind furniture
  • under baseboards
  • in closets

You may not notice a bite from a hobo spider at first, but it’ll cause pain and numbness within 15 minutes.

After 1 hour, the site will start to turn red. In 8 hours, it’ll become hardened and swollen. After 24 to 26 hours, the wound may discharge fluids and eventually turn black.

Other signs and symptoms may include:

  • a red or purple blister at the puncture site
  • visual or aural disruption
  • weakness
  • joint pain
  • headaches
  • nausea
  • sweating

Hobo spider bites are slow to heal. Seek immediate medical treatment if you suspect a hobo spider has bitten you.

The treatment is similar to that of brown recluse spider bites. It may involve:

Treatment works best if administered within 24 hours of the bite.

What else should you know about a hobo spider bite?

Tarantulas occur in southwestern states with desert climates and as far east as the Mississippi River. They tend to hide under:

  • logs or stones
  • tree trunks
  • in tunnels or burrows

Most tarantula bites in the United States are from pet tarantulas.

You can usually identify tarantulas by their appearance.

They have:

Tarantulas aren’t aggressive. The venom from the species found in the United States isn’t considered dangerous. Their bite may be painless or feel like a bee sting. The area will become warm and red.

Other potential symptoms can appear several hours or even days later and include:

Seek medical attention immediately if you experience any of these symptoms.

The Brazilian wandering spider is native to Central and South America. It moves quickly and aggressively. The body of a wandering spider is around one-quarter to one-and-a-quarter inches long. It’s considered one of the most venomous spiders in the world.

The bite of a Brazilian wandering spider is extremely painful. It can quickly result in heavy sweating and drooling. The skin around the bite will usually swell, turn red, and get hot.

In severe cases, the bite can result in dead tissue or death.

Seek emergency treatment immediately. Antivenom is available for this spider’s bite.

Common all over the country, wolf spiders have a body length of one-quarter to one-and-a-third inches and look similar to tarantulas. They like to stalk their prey by hunting on the ground.

You’ll find them:

  • in sand and gravel
  • around the bases of doors and windows
  • in house plants

Look for two large eyes in the middle of their faces, accompanied by six smaller eyes.

A wolf spider’s bite may tear the skin and cause pain, redness, and swelling. You may also experience swollen lymph nodes as a result of the bite.

For some people, healing can take up to 10 days. In rare cases, the bite can lead to tissue damage.

What do you need to know about a wolf spider bite?

One of the most common household spiders, the jumping spider exists throughout the United States. Around one-fifth to three-quarters of an inch long, it has a stout, hairy body.

The most common type is black with white spots on top. It moves erratically and actually jumps as a method of moving between locations. You’re likely to find it outside in gardens and near other vegetation.

The jumping spider’s bite is usually no worse than a wasp sting. It can be dangerous if you’re allergic to spider venom.

Serious symptoms include:

  • pain
  • itching
  • redness
  • swelling
  • headaches

They’ll attack if threatened, so use gloves when gardening.

How do you treat a jumping spider bite?

The sand-colored camel spider lives in desert climates and has a powerful pincer on its head. They occur in central and southern Mexico and the western United States.

A camel spider will always seek the coolest place around, which just may be your shadow. A fast runner (up to 10 mph), some can grow to over 2 inches long.

Because of its large jaws, a camel spider can leave a significant wound in human skin. These spiders don’t produce venom, but you may get an infection due to the open wound.

You may also experience swelling around the bite wound and mild to intense bleeding.

Always seek medical attention if you suspect you or someone else has symptoms of a spider bite.

Call 911 if the person has:

  • an allergic reaction, including hives, swelling, and breathing difficulty
  • shock or breathing problems, even if these do not appear to be an allergic reaction
  • muscle cramps
  • fever
  • loss of consciousness
  • severe or rapidly worsening pain, swelling, or other symptoms

If you see the spider, try to take a photo in case you need to show it to a doctor later for identification.

You may need a tetanus booster if you haven’t had one in the last 10 years.

For the best outcome, seek treatment for a spider bite within 24 hours of being bitten.

What can you do at home to ease the effect of a spider bite?

Spiders may be present in the home, in yards, outdoors, and in workplaces.

Here are some tips to reduce the risk of a spider bite:

  • known how to identify venomous spiders in your local area
  • take care when outdoors hiking or camping or at home working in the yard
  • be vigilant when disturbing items or places that have not been disturbed for some time, such as a log pile or an attic
  • inspect or shake out any clothing, shoes, boots, and equipment before use, especially if stored in sheds and outhouses
  • wear protective clothing, with long sleeves, gloves, and so on, during yard work and on hikes
  • keep the yard clear of debris, as far as possible
  • ensure you have a tetanus booster every 10 years

How do you know if a spider bit you?

You will not always know if a spider has bitten you, although some bites cause pain, like a sting. You may notice two puncture marks on the skin. In some cases, there will be a reaction either at once or after some hours, but it depends on the type of spider.

A bite from a wolf spider, for example, can tear the skin and cause pain, redness, and swelling. The bite of a jumping spider may cause pain similar to a wasp sting, and people with an allergy can have a reaction.

How do you tell if you were bitten by a venomous spider?

Symptoms vary widely and depend on the type of spider but include:

  • itching, pain, and a rash
  • muscle pain or cramps
  • sweating, fever, and chills
  • breathing problems
  • anxiety
  • high blood pressure

You may not notice a bite from a brown recluse spider at once, for example, but pain and itching may occur after some hours. A bite from a black widow spider may feel like a pinprick at the time, but puncture marks will be visible, and other symptoms will likely follow, such as muscle cramps and a fever.

How long after a spider bite do symptoms occur?

It will depend on the spider. Some spider bites cause an immediate reaction. Others are painless at the time, while others cause immediate pain and swelling. Symptoms of some venomous spider bites may not appear for several hours. A reaction from a brown recluse spider bite may develop after 2 to 8 hours. Cramping and other symptoms of a black widow spider bite usually start within an hour. A tarantula bite may be painless, but symptoms can appear several hours or days later.

What can be mistaken for a spider bite?

Spider bites often look like other bug bites, but sometimes two puncture marks will be visible. Further reactions can occur, such as swelling, pain, fever, and other symptoms, depending on the spider.

Why is it bad to squeeze a spider bite?

Squeezing a spider bite will not help reduce the risk of symptoms but may spread the venom or any infection further. Instead, wash the area with soap and water and keep it raised, if possible. Apply a damp cloth to reduce swelling, and seek medical attention as soon as possible.

Most types of spiders in the U.S. will not bite a human. Their mouths are too small, and their fangs are not strong enough to pierce the skin. Some do bite, but their toxin is not strong enough to cause a serious reaction in humans.

However, the bite of a few spiders — such as the black widow and the tarantula — can cause serious harm to humans. Anyone with a severe reaction to a spider bite should seek immediate medical help.