What Does a Spider Bite Look Like? Signs, Symptoms, and When to Seek Treatment (With Pictures)

The thought of a spider bite and the harm it could cause can be scary. Although there are thousands of species of spiders in the world, only a handful of spiders are poisonous to humans. 

Almost all spiders make some type of venom. But spider bites aren’t usually dangerous. That’s because their fangs are either too short or delicate to break the skin, or their venom doesn’t affect people. Fortunately, very few poisonous spiders are found in North America. 

Even though there are few poisonous spiders, their bites have to be taken seriously. Left untreated, spider bites can become infected or cause serious tissue damage. Very rarely, a spider bite could be deadly. Let’s take a closer look at spider bites and what to do if you’ve been bitten.

How do I know if I got bit by a spider?

Sometimes, it’s really hard to know if you’ve been bitten by a spider — especially because signs of most spider bites aren’t very specific. Common spider bite signs to look for include:

• Sudden pain or itching

• Two small breaks in the skin or a small red bump

• Redness

• Swelling

• Target-shaped or bull’s-eye rash on the skin

• Dark or discolored area on the skin

• Development of an ulcer in 3 to 4 days

• Development of muscle cramps, headache, and/or severe pain

Spider bite symptoms can sometimes look similar to injuries caused by other biting insects or other skin trauma. But the mark on your skin could be a spider bite if:

• You see a spider on you

• You’ve been in an environment where spiders like to hang out

Things that increase the likelihood you’ve been bitten by a spider include:

• Being in secluded, dark places (like attics, barns, or cellars)

• Being in tall grass or wood piles

• Putting on clothes or shoes without shaking them out first

Symptoms of a dangerous spider bite

Here are some symptoms of a dangerous spider bite. If you notice any of these, seek immediate medical care: 

• Nausea, vomiting, or diarrhea

• Weakness

• Fever

• Feeling lightheaded, drowsy, or faint

• Headache

• Muscle spasms

• Rapid swelling, a large sore, or black tissue at the site of the bite

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What does a spider bite look like?

Spider bites don’t all look the same. And they can look different on different people. Spider bites may look different depending on:

• What type of spider caused the bite

• How much time has passed since the bite took place

• How much venom was injected

• How strongly you react to the venom 

Here are what some common spider bites can look like, followed by different pictures. 

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Spider bite rash

A spider bite rash can range in color from pink, red, violet, or brown. It can also have different appearances, including:

• A bull’s-eye rash

• A firm, smooth bump

• A flat, spreading rash

• A dark crust surrounded by skin discoloration

Fang or bite marks

Sometimes, it’s possible to see the actual fang marks left by the spider. These usually look like two tiny, side-by-side holes in your skin. 

Swelling blisters and lesions

Spider bites can also cause fluid-filled blisters and skin sores. These may be surrounded by red, brown, or black skin discoloration. 

Spider bite pictures

Here are some spider bite pictures to help you identify signs of different types of spider bites. 

Two small blisters at the site of spider bite surrounded by redness and swelling.

A red rash surrounding a spider bite (also known as a bullseye rash).

A spider bite causes a crusty and bloody skin wound surrounded by redness.

A skin wound (ulcer) caused by a spider bite.

Black widow and brown recluse bites

Two of the most common dangerous spider bites are from brown recluse and black widow spiders. Here are some signs to look for. 

Brown recluse spider bites

A brown recluse spider bite is usually painless at first. But then it can become inflamed and painful. The bite can cause localized tissue death, which leads to blistering, an open sore, and black skin. More serious symptoms are less common, and they usually happen within 3 to 7 days. These can include:

• Fever

• Chills

• Nausea and/or vomiting

• Joint pain

• Seizures

Black widow spider bites

A black widow spider bite usually hurts right away, even though there may not be a lot of skin inflammation or discoloration. Within 2 hours, the following symptoms may occur:

• Pain throughout the body

• Muscle cramps

• Nausea and/or vomiting

• Trouble breathing

• Fever

Which spiders are most likely to bite?

According to experts, spiders in the U.S. aren’t normally aggressive. But any spider can bite, especially if it’s being disturbed. Although rare, the most dangerous spider bites are ones caused by brown recluse and black widow spiders. Although less severe, common bites also come from these spiders:

• Wolf spider

• Garden spider 

• Trapdoor spider

• Mouse spider

• Huntsman spider

• Running crab spider

• Green lynx spider

• False black widow spider

• Jumping spider

• Tarantula

• Orb-weaver spider

• Crab spider

• Parson spider

Keep in mind that if you’re allergic to the venom, even a normally mild spider bite can be serious. In rare cases, they can cause severe allergic reactions, like anaphylaxis (more on this below).

What to do if you suspect you’ve been bitten by a spider

Most spider bites are harmless. But any break in the skin can lead to an infection. Following these simple steps will help control pain and reduce the risk of infection:

• Wash the area with soap and water right away.

• Place an ice pack on the area of the bite.

• Take an over-the-counter pain medication, if needed. Acetaminophen (Tylenol) or Ibuprofen (Motrin, Advil) are good options.

• Use an antihistamine like diphenhydramine (Benadryl) for swelling.

• Get medical attention for young children or adults with serious symptoms.

• Get a tetanus booster if your vaccines aren’t up to date.

How do I know if a spider bite is getting infected?

Despite your best efforts to clean the area, a spider bite could still get infected. Some of the signs of a spider bite infection include:

• Redness or swelling extending out from the bite

• Warmth in the area

• Pain

• Yellowish drainage (pus)

• Fever

Signs of an infected spider bite can overlap with signs of the bite itself. The thing to keep in mind is that most spider bites should get progressively better after a day or two. If the symptoms are getting worse, it could be a sign of infection or that a venomous spider caused the bite.

When to seek medical treatment for a spider bite

It’s important to take all spider bites seriously. Fortunately, you can treat most spider bites at home. But sometimes you may need to get medical treatment. Here are some things that should prompt you to seek medical treatment:

• You recognize the spider as being poisonous (or if you suspect it is).

• You experience headache, abdominal cramping, or nausea and vomiting.

• You feel pain that continues to get worse or spreads elsewhere on your body.

• You see yellowish discharge (pus) drains from the area, or the bite becomes an open sore.

• You have fever, chills, joint pain, or body aches. 

• You feel pain, redness, or swelling that continues to get worse after 24 hours.

In rare cases, spider bites are a medical emergency. You should get immediate care if you have any of these signs of a severe allergic reaction:

• Rapid heart rate

• Trouble breathing or swallowing

• Chest tightness

• Swelling of your mouth or face

Why trust our experts?

Written by:

Frank Schwalbe, MD

Frank Schwalbe, MD, is an assistant professor of anesthesiology at the Yale School of Medicine. He has practiced anesthesiology for 30 years.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

Reviewed by:

Maria Robinson, MD, MBA

Maria Robinson, MD, MBA, is a board-certified dermatologist and dermatopathologist who has practiced dermatology and dermatopathology for over 10 years across private practice, academic, and telehealth settings. She is a fellow of the American Academy of Dermatology and the American Society of Dermatopathology.

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