Spider Bite First Aid: What to Do, Black Widow and Brown Recluse Warning Signs and When to Get Care
This post may contain affiliate links, full disclosure here.
Quick answer: most spider bites cause only mild redness, swelling and pain, much like a bee sting. Wash the bite with soap and water, apply a cool compress, raise the area if it is on an arm or leg, and take an over-the-counter pain reliever if needed. Get medical care quickly if you think a black widow or brown recluse bit you, or if there is severe pain, muscle cramps, sweating, trouble breathing, a spreading wound or signs of infection. Call Poison Control at 1-800-222-1222 for advice, or 911 for trouble breathing or a severe reaction.
Spiders live almost everywhere, including city apartments, basements, storage units and laundry rooms. The vast majority are harmless to people, and most never bite. In the United States, only a few kinds of spiders have venom that can cause serious illness. This article is part of our emergency first aid guide for city households, and it covers how to treat bites, which spiders to watch for and when to get help.
Sources: Centers for Disease Control and Prevention (CDC) National Institute for Occupational Safety and Health (NIOSH) guidance on venomous spiders; America’s Poison Centers; American Academy of Dermatology information on spider bites; MedlinePlus (U.S. National Library of Medicine) entries on black widow and brown recluse spider bites; university extension entomology programs. This article is general information, not medical advice.
How Common Are Dangerous Spider Bites?
Spiders generally bite only when they are trapped or pressed against skin, such as when someone puts on a shoe, rolls over in bed or reaches into a dark storage box. Most spiders have fangs too small or weak to pierce human skin, or venom that is not harmful to people.
In the United States, the spiders most often linked to serious bites are widow spiders, including the black widow, and recluse spiders, including the brown recluse. Even with these spiders, most bites do not cause life-threatening illness, but they can need medical treatment.
First Aid for Any Spider Bite
For a bite from an unknown or harmless spider:
- Move away from the spider to avoid more bites.
- Wash the bite gently with soap and water.
- Apply a cool compress or a cloth-wrapped cold pack for about 10 minutes at a time to reduce swelling and pain.
- Elevate the area if the bite is on an arm or leg.
- Take an over-the-counter pain reliever if needed, following the label.
- Apply antibiotic ointment if the skin is broken, and keep the area clean.
- Watch for changes over the next few days.
Do not cut the bite, try to suck out venom or apply a tourniquet. These steps do not help and can cause harm.
Keep an eye on the bite for the next several days. A small red bump that slowly fades is normal. A bite that becomes more painful, larger, darker or warm to the touch, or that drains pus, needs a doctor to take a look. Mark the edge of any redness with a pen so you can tell whether it is spreading.
If it is safe, take a photo of the spider or capture it in a sealed container. This can help health professionals identify it. Do not risk another bite to do so.
Black Widow Spiders
How to recognize them
Female black widows are shiny black with a red or orange hourglass shape on the underside of the abdomen. Some have red spots instead of a full hourglass. Males are smaller and usually harmless. Black widows build messy, irregular webs in sheltered places, such as woodpiles, sheds, garages, under outdoor furniture and in cluttered basements.
Symptoms of a bite
The CDC notes that black widow venom affects the nervous system. A bite may feel like a pinprick at first, followed by:
- Pain, redness and swelling at the bite
- Muscle pain and cramping, often in the abdomen, back, chest or thighs, starting within an hour or so
- Sweating
- Nausea and vomiting
- Headache
- Restlessness
- Increased blood pressure and heart rate
What to do
Seek medical care promptly. Wash the area, apply a cool compress and keep the person calm while you get help. Call 911 if the person has trouble breathing, chest pain or severe symptoms. Children, older adults and people with heart conditions may be at higher risk of serious effects. Doctors can treat pain and muscle spasms, and an antivenom exists for severe cases.
Brown Recluse Spiders
How to recognize them
Brown recluse spiders are tan to dark brown with a darker violin-shaped marking on the top of the front body section, with the neck of the violin pointing toward the rear. A key feature is their eyes: brown recluses have six eyes arranged in three pairs, while most spiders have eight. They are native mainly to the south-central and midwestern United States, and they prefer dark, undisturbed places such as closets, attics, boxes and behind furniture.
Symptoms of a bite
Brown recluse bites are often painless at first. Over the following hours, the area may become red, painful and itchy. In some cases, a blister forms and the center darkens as tissue dies, leaving an open sore that can take weeks or longer to heal. Rarely, people develop body-wide symptoms such as fever, chills, nausea, joint pain or a rash.
What to do
Wash the area, apply a cool compress, elevate it and seek medical care, especially if the wound worsens, a blister or dark center develops, or you have fever or feel unwell. Children are at greater risk of serious body-wide reactions and should be seen by a doctor.
Many "Spider Bites" Are Not Spider Bites
Doctors and dermatologists often point out that many skin sores blamed on spiders are actually caused by something else, most commonly bacterial skin infections, including those caused by methicillin-resistant Staphylococcus aureus (MRSA). Other insects, such as bed bugs, fleas and mosquitoes, and conditions like allergic reactions can also look like bites.
This matters because a skin infection may need antibiotics or drainage, and treating it as a simple bite can delay care. Be suspicious of an infection if:
- You never saw a spider
- The sore is red, warm, swollen and painful, with pus
- The redness is spreading
- You have a fever
See a doctor promptly if any of these apply. Our guide to cuts and scrapes wound care explains how to watch for infection.
When to Get Emergency Help
Call 911 if the person has:
- Trouble breathing or swallowing
- Swelling of the face, lips, tongue or throat
- Chest pain or a racing heartbeat
- Severe muscle cramps or rigid abdominal muscles
- Confusion, fainting or seizures
Allergic reactions to spider bites are uncommon, but if someone has signs of anaphylaxis, use their epinephrine auto-injector if they have one and call 911. Our guide to anaphylaxis first aid explains the warning signs.
When to Call Poison Control or a Doctor
Poison Control specialists can help with bites and stings as well as swallowed substances. Call 1-800-222-1222 if:
- You think a black widow or brown recluse bit you
- Pain is severe or getting worse
- The bite area is changing color or forming a blister or sore
- You are not sure what bit you and are worried
Our guide to when to call Poison Control explains how the service works. It is free and confidential and open around the clock.
Keeping Spiders Out of an Apartment
You cannot keep every spider out, and most are harmless and even helpful because they eat other insects. But you can reduce the chance of an unpleasant surprise:
- Reduce clutter, especially in closets, under beds and in storage areas.
- Store items in sealed plastic bins instead of cardboard boxes.
- Shake out shoes, gloves and clothing that have been stored or left on the floor.
- Move beds a few inches from the wall and keep bedding off the floor.
- Wear gloves when reaching into storage units, boxes or woodpiles.
- Seal cracks around windows, doors and pipes.
- Vacuum webs and egg sacs regularly.
- Use sticky traps along walls in basements and storage areas to monitor activity.
- Report heavy infestations to your landlord or building management, who may arrange pest control.
Other Spiders People Commonly Worry About
Several other spiders often cause concern, but they are much less likely to cause serious problems.
Wolf spiders
Wolf spiders are large, hairy, brown or gray spiders that hunt on the ground rather than spinning webs. They often wander indoors in fall. Their size can be alarming, and a bite can be painful, but wolf spider venom is not considered dangerous to people. Treat a bite with the basic first aid steps above.
Jumping spiders
Jumping spiders are small, compact and often brightly marked, with large front eyes. They are curious and active during the day. They rarely bite, and when they do, the effects are usually mild.
Yellow sac spiders
Yellow sac spiders are pale yellow or beige and often found indoors along ceilings and walls. Their bites can cause local pain, redness and swelling. Most heal without problems, but watch any bite for signs of infection.
Hobo spiders
Hobo spiders live in parts of the Pacific Northwest and were once widely blamed for wounds similar to those of brown recluse bites. More recent research has questioned whether they cause serious harm. Still, if any bite forms a spreading wound, see a doctor.
Cellar spiders
Often called daddy longlegs, cellar spiders have tiny bodies and very long legs and build loose webs in corners and basements. A common myth claims they are highly venomous but unable to bite people. In reality, there is no evidence that they pose any danger to humans.
Shared Spaces in Apartment Buildings
In apartment buildings, many spider encounters happen in shared spaces rather than in individual units. Laundry rooms, basement storage cages, bike rooms, trash rooms and boiler rooms tend to be dark, quiet and full of places for spiders to hide.
When using these spaces, turn on lights before reaching into corners, and avoid putting your hands where you cannot see. Keep belongings in storage cages in sealed bins, and shake out any items you bring back to your apartment. If you notice many webs or spiders, especially in parts of the country where black widows or brown recluses live, let building management know. They can schedule cleaning and pest control for common areas, which you usually cannot do yourself. Many leases and local housing codes make the landlord responsible for pest control in shared areas, so a written request with the date and location of what you saw helps create a record and gets the problem handled sooner.
Spider Bites in Children and Pets
Young children may not be able to tell you they were bitten. Watch for sudden crying, a red or swollen spot, unusual irritability, belly pain or muscle stiffness, especially after playing in a garage, basement or yard. Seek medical care promptly if you suspect a black widow or brown recluse bite in a child.
Pets can also be bitten. Contact your veterinarian if your pet has sudden pain, swelling, muscle tremors or seems unwell after contact with a spider. Our guide to animal bites first aid covers other bites involving pets.
Frequently Asked Questions
How do I know if a spider bite is serious?
Severe pain, muscle cramps, sweating, a spreading or darkening wound, fever or trouble breathing are warning signs. Get medical care if any of these appear.
How long does a spider bite take to heal?
Most harmless bites improve within a few days. Brown recluse wounds that form an open sore can take weeks or longer and need medical follow-up.
Should I put ice on a spider bite?
A cold pack wrapped in a cloth can ease pain and swelling. Do not put ice directly on the skin.
Do I need to bring the spider to the doctor?
It can help with identification, but only if you can capture it safely. A clear photo also works.
Are house spiders dangerous?
Most common house spiders are harmless. In parts of the country where brown recluse spiders live, they can be found indoors in undisturbed areas.
