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

Spider bites can sound scary. But although there are thousands of spider species in the world, only a handful are actually poisonous to humans. Most spiders aren’t dangerous because their fangs can’t easily break the skin or their venom doesn’t affect people. Fortunately, very few poisonous spiders are found in North America. 

Still, some spider bites can cause infection, skin damage, or more serious symptoms. And, sometimes, it’s hard to know if a spider actually bit you at all. That’s because most spider bites cause nonspecific symptoms like redness, swelling, itching, and pain. 

Here, we’ll review what a spider bite can look like (including spider bite pictures), signs to watch for, and when to seek medical care.

What does a spider bite look like?

Identifying spider bites can be hard. They don’t all look the same, and they can appear differently from person to person. A spider bite’s appearance may depend on: 

• What type of spider caused the bite

• How much time has passed since the bite 

• How much venom the spider injected

• How strongly your body reacts to the venom 

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

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.

Symptoms of a dangerous spider bite

Most spider bites are mild and improve on their own. But, some can cause serious symptoms that need medical attention. Seek immediate medical care if you notice any of the following after a spider bite:

• 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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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

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. Less severe spider bites commonly come from any of 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).

How to treat a spider bite

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 (OTC) pain medication, if needed, like acetaminophen (Tylenol) or ibuprofen (Motrin, Advil). 

• Use an antihistamine like diphenhydramine (Benadryl) to help with itching or 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 signs of a spider bite infection include:

• Redness or swelling extending out from the bite

• Warmth in the area

• Increasing pain

• Yellowish drainage (pus)

• Fever

Some of these symptoms can overlap with the bite itself. But most spider bites should start improving within a day or two. If the area keeps getting worse instead of better, it could be a sign of infection or a bite from a venomous spider.

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 you suspect it is).

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

• The pain gets worse or spreads to other parts of your body. 

• The bite becomes an open sore or starts draining pus (yellow discharge). 

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

• Pain, redness, or swelling continues to worsen 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

Frequently asked questions

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:

Sophie Vergnaud, MD

Sophie Vergnaud, MD, is the Senior Medical Director for GoodRx Health. A pulmonologist and hospitalist, she practiced and taught clinical medicine at hospitals in London for a decade before entering a career in health education and technology.

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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