Brown Recluse Spiders: What to Know

Medically Reviewed by Jabeen Begum, MD on May 21, 2024
Written by Kristin Mitchell, WebMD Editorial Contributor, Deanna Altomara
8 min read

Brown recluse spiders (Loxosceles reclusa) are the most common brown spider in the U.S. As their name suggests, these spiders prefer to be left alone. They tend to live in indoor and outdoor spaces where people don’t go most of the time. 

If the spider feels trapped, especially when it’s pressed between your skin and clothing or bedding, it may bite you.

Brown recluse spiders are one of two spiders found in the U.S. that can cause real trouble if they bite you. They make harmful venom that may cause a painful sore at the site of the bite. It may cause even more severe symptoms in some people. If you have a run-in with a brown recluse, it’s wise to have a doctor check you out, just in case.

What does a brown recluse spider look like?

Brown recluse spiders are light brown. A mature spider has a dark violin-shaped area on its back, right behind the eyes (but young spiders don’t have this mark yet).

It may be bigger than other spiders that you’re used to seeing. Its body can range in size from 1/4 to 1/2 inch, and its long legs make it appear even larger. Its legs aren’t spiny or banded, which can help you tell it apart from similar spiders.

Also, most spiders have eight eyes, but a brown recluse spider has six. Two are in the front, and there are two more on each side of its head.

Where do brown recluse spiders live?

Brown recluses are found mostly in the Midwest and the South. The spider favors indoor spaces, such as attics, garages, or dark closets. In particular, they settle in old furniture, cardboard boxes, shoes, empty spaces between walls, and wood framing. Outdoors, it hides in out-of-the-way places — under logs, beneath porches, or within piles of rocks.

Females make flat webs to catch food, but male spiders go out to hunt. Brown recluse spiders are nocturnal, which means they’re active at nighttime.

Are brown recluse spiders poisonous?

Brown recluse spiders are venomous. This means that when they bite you, they inject a toxic venom. This venom can kill cells and cause an immune reaction (for example, swelling and redness). But because spiders inject such a tiny amount of venom, their bites are usually harmless.

Female brown recluse spiders have more venom, so their bites may be more likely to cause problems. In rare cases, brown recluse bites can cause the skin and tissue around the bite to fester and die.

Brown recluse venom is most dangerous for children. In rare cases, children can get serious complications and even die from a brown recluse bite.

Getting a spider bite can be scary. The good news is, most bites are harmless to adults. 

But these bites can be very serious in children, older adults, and people with preexisting medical conditions. If a child gets bitten, take them to the emergency room.

Here is what you should do for first aid, regardless of age:

  1. Don’t panic. If you can, take a picture of the spider. This will help the doctor know what kind of treatment to give you.
  2. Wash the bite. Use soap and water.
  3. Make a cold compress. Wet a cloth with cold water (or fill the cloth with ice). Put it on the bite.
  4. Raise the bite above heart level, if possible. Don’t try to remove the venom. 
  5. Call a doctor or Poison Control (1-800-222-1222). Try to get an appointment for the same day. They can give you more advice. In the meantime, you can take acetaminophen (Tylenol).

In rare cases, adults can get a serious brown recluse spider bite. Call your doctor or go to the emergency room if you have:

  • Signs of infection (such as oozing cloudy fluid)
  • Extreme pain
  • Trouble breathing
  • Fever
  • Dizziness
  • Chills
  • Nausea

If you aren’t up-to-date with your tetanus booster, now is a good time to get one. Some spider bites have tetanus spores, which can cause a serious infection.

Most brown recluse spider bites aren’t serious. They may just cause some redness and swelling. But if the spider injected a lot of venom (this is more common for females), the bite could be more severe. It’s rare for brown recluse bites to cause large, festering wounds.

Brown recluse spider bites are usually painless, but some people notice a stinging feeling. Symptoms such as burning and itchiness usually develop about 2-8 hours after a bite.

It’s uncommon, but some people get symptoms such as:

  • Fever
  • Chills
  • Nausea
  • Cramps
  • Joint pain
  • Weakness
  • Dizziness
  • Restlessness or trouble sleeping
  • Seizures or coma (very rare)

These bodywide symptoms are more likely to occur in children. They are also more severe. If a spider bite causes these symptoms, especially in children, call a doctor or go to the emergency room right away.

What does a brown recluse spider bite look like?

Initially, the bite site is mildly red and upon close inspection may reveal fang marks. Within a few hours, the red area will get larger and the center will become pale, causing a "bull's-eye" appearance.

Brown recluse spider bite stages

Brown recluse bites change over time. Here’s what you can expect:

  • The bite: Usually, the bite itself is painless. But some people notice a stinging feeling.
  • Within an hour: The bite area will become red. You might be able to see two fang marks.
  • In 2-8 hours: The red area will get bigger, while the center of the bite will become pale. This ring will form a “bull’s-eye.” You may also get a bruise and pain at the site. Some people also get muscle pain, nausea, headaches, or fatigue. These symptoms are more severe in children and can lead to seizures and other complications.
  • The next few days: The bite will form a white blister, then a 2-inch wide, hard, scabby lump. The center of the wound will sink (like a crater) and turn dark blue, purple, or black. For mild bites, the pain will start to go away.

  • The next few weeks: As the wound heals, the dead skin will peel. Call your doctor if the wound is getting worse, is painful, or looks bad. Severe wounds may require skin graft surgery.

    It usually takes about 8 weeks to heal.

When you go to the doctor, tell them about what happened and what your symptoms are. If you saw the spider, try to describe what it looked like (a picture may help). This can help the doctor figure out what type of spider bit you and how to treat you.

Usually, no further testing is necessary. But if you have symptoms such as fever, headache, or muscle pain, your doctor might suggest getting some blood work.

Spider bites look very similar to sores caused by other conditions, such as diabetes and Lyme disease. In fact, many sores are often mistaken as brown recluse bites. So, your doctor might try to rule out these conditions.

Depending on the severity of the bite, the doctor may want to follow up with you as it heals.

In children

Brown recluse venom can cause dangerous complications in children. If you think a child was bitten by a brown recluse, go to the emergency room. Depending on how severe the bite is, they may need hospitalization or skin graft surgery.

In adults

For adults, most brown recluse spider bites can be treated at home with good results. But less than about 10% of them cause ulcers or blisters that damage your skin so badly that you need a doctor’s care. In this case, you may need a skin graft. This is when a surgeon takes a healthy piece of skin from a different part of your body and uses it to cover the wound. The surgery will probably take place 4-6 weeks after the bite, as doing it too early could cause problems.

Spider bites can become infected. Some spiders can spread tetanus, so you may need a tetanus booster. If you have an infection, you may need antibiotics.

Get emergency help right away if you:

  • Have a small child who is bitten
  • Are older or have preexisting conditions
  • Are in extreme pain
  • Have trouble breathing
  • Have a fever, dizziness, nausea, or other body-wide symptoms
  • Have signs of infection (such as cloudy liquid oozing from the wound)

Brown recluse spider bite home treatment

If your symptoms are mild, try these simple home remedies:

  • Clean it with soap and water.
  • Apply antibiotic cream.
  • If you were bitten on an arm or leg, keep it raised while you’re resting. This can reduce swelling.
  • Put ice on it.
  • Take over-the-counter pain medicine, such as acetaminophen. Antihistamines can also help.
  • Watch for more severe symptoms.

Brown recluse spider bites medication

Brown recluse antivenom isn’t available in the U.S. But acetaminophen can ease spider bite symptoms. If the bite is itchy, you can also try an antihistamine (allergy medicine). Steroids generally won’t help.

If the bite becomes infected, your doctor will probably prescribe antibiotics.

Brown recluse spider bites prevention

The best way to treat a spider bite (or any injury) is to prevent it in the first place. Here are some tips to stay safe:

  • Shake out towels, blankets, shoes, or clothing before you use them
  • Wear a long-sleeved shirt, pants, gloves, boots, and a hat in dark, out-of-the-way places and when handling boxes you haven’t touched in a while.
  • When stacking boxes, take care to minimize empty spaces.
  • Keep outdoor work areas tidy and free of tall grasses.
  • Store things in airtight plastic bags.
  • Put firewood at least 20 feet away from your house.
  • Seal cracks and small openings in your home.
  • Stay up-to-date with your tetanus shot, as spider bites can sometimes become infected.
  • If you think you have an infestation, call a pest control company.

Most brown recluse spider bites are harmless. But in rare cases, they can be serious. If you get bitten, clean the wound and call your doctor. If your child is bitten by a brown recluse, go to the emergency room.

What will happen if you get bitten by a brown recluse spider?

Most brown recluse bites aren’t serious and can be treated at home. However, some people may develop complications such as fever, nausea, and seizures. 

Which states have brown recluse spiders?

Brown recluse spiders are typically found in Louisiana, Arkansas, Missouri, Alabama, and in certain parts of California, Nevada, New Mexico, Arizona, Texas, Oklahoma, Kansas, Iowa, Illinois, Indiana, Ohio, Kentucky, Tennessee, Georgia, and Florida.

How do you tell if it’s a brown recluse?

These spiders are light brown with a dark violin-shaped mark on their backs. You can tell them apart from other spiders because they have six eyes (not eight) and don’t have spiny or banded legs.