Are most spiders poisonous?
The majority of the 3,000 spiders in the United States aren’t poisonous. Even if most spiders did bite, their fangs are too small or weak to puncture human skin. Their bites may leave itchy, red wounds that heal within a week or so.
The spiders that do manage to bite through our skin and insert toxic venom can cause serious health complications. Read on to learn what spider bites look like, what varieties of spider leave certain bites, and how to treat spider bites.
What do spider bites look like?
Identifying a spider bite is easiest if you saw the spider that bit you, but it’s possible that you won’t notice the wound until hours later. Look for things like swelling, a red welt, skin damage, and any troubling symptoms that accompany the bite.
Other possible symptoms that accompany spider bites include:
- itching or rash
- pain around the area of the bite
- muscle pain or cramping
- blister that’s red or purple in color
- difficulty breathing
- nausea and vomiting
- anxiety or restlessness
- swollen lymph glands
- high blood pressure
Spider bites often take longer to heal than other insect bites, and they may affect skin tissues. It’s important to keep the bite clean to reduce the risk of infection.
How to treat a spider bite at home
In some cases, you can treat spider bites at home. For nonvenomous spider bites, follow these steps:
- Apply an ice pack on and off for 10 minutes at a time.
- Elevate the area to reduce swelling.
- Take an antihistamine to help with itching.
- Clean the area 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 you’ve been bitten by one of the following species:
- brown recluse
- black widow
- hobo spider
- Brazilian wandering spider
Learn where these spiders hide and what they look like below.
About an inch long and usually nonaggressive, the brown recluse typically hides in dark, secluded spaces. It only bites if it’s trapped against your skin. 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:
- eastern Texas
The initial brown recluse bite may be painless, but within eight hours it will begin to itch, hurt, and turn red. A red or purple ring resembling a target or bull’s-eye will develop around the bite. This 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 is no antidote for a brown recluse bite, but treatment like keeping the area clean can encourage faster healing. Your doctor will examine the bite and prescribe antibiotics. In extreme cases, such as tissue death, you will need surgery and hospitalization.
The black widow spider is shiny and black with a distinct, reddish, hourglass-shaped mark on its belly. Found mostly in the warm southern and western states, the black widow stays in secluded spaces like piles of fallen leaves, woodpiles, and 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 and you’ll be able to see the two puncture marks on your skin.
Symptoms of a black widow bite include:
- muscle cramping
- pain and burning at puncture site
- high blood pressure
- increase saliva and sweating
- nausea and vomiting
Prompt treatment is best, especially for children and older adults. In some cases, a healthcare professional will prescribe antivenin to remove the venom from your body.
Hobo spiders are common in the Pacific Northwest. They sit up high on long legs and run fast. Watch out if you’re cleaning window wells or sweeping out the garage, as they may attack when provoked. Hobo spiders lurk behind furniture, under baseboards, and in closets.
A bite from a hobo spider may be unnoticeable at first, but it will cause pain and numbness within 15 minutes. After one hour, the site will start to turn red. In eight hours, it will become hardened and swollen. After 24–26 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
- joint pain
- low blood cell count
Hobo spider bites are slow to heal. Seek immediate medical treatment if you suspect you’ve been bitten by a hobo spider. The treatment is similar to that of brown recluse spider bites and may involve corticosteroids, antibiotics, or surgery. It also works best if administered within 24 hours of the bite.
Southwest states with desert climates host tarantulas, but tarantulas may also be found as far east as the Mississippi River. They tend to hide under logs or stones, tree trunks, and in tunnels or burrows. You can usually identify them by their size (from 3 to 5 inches long), hairy texture, and visible fangs that hang down.
Tarantulas aren’t aggressive, and the venom of the spiders found in the United States isn’t considered dangerous. Their bite will feel like a bee sting, and the area will become warm and red.
Other potential symptoms include:
Seek medical attention immediately.
Brazilian wandering spider
Native to Central and South America, this spider moves quickly and aggressively. It can grow up to 5 inches long, and it’s considered one of the most poisonous spiders in the world.
The bite of a Brazilian wandering spider is extremely painful and 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. An antivenin is available for this spider’s bite.
Common all over the country, wolf spiders measure three to 4 inches long and look similar to tarantulas. They like to stalk their prey by hunting on the ground, and you’ll find them in sand and gravel, around the bases of doors and windows, or 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 glands as a result of the bite. For some people, healing can take up to 10 days. In rare cases, the bite can cause tissue damage.
Found in desert climates, the sand-colored camel spider has a powerful pincer on its head. A camel spider will always seek the coolest place around, which just may be your shadow. A fast runner (up to 10 mph), it may be only 2 to 3 inches long, but in some locations, it grows up to 6 to 8 inches in length.
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.
One of the most common household spiders, the jumping spider exists throughout the United States. Usually only a half-inch long, it has a stout, hairy body. The most common type is black with white spots on top. It moves erratically in a manner that resembles jumping. 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 poisonous if you’re allergic to spider venom. Serious symptoms include:
They will attack if threatened, so use gloves when gardening.
When to see a doctor
Call 911 if you or someone you know is showing signs of full-body shock or having trouble breathing. Always seek medical attention if you suspect you are feeling symptoms from a spider, or if the symptoms don’t go away over time. For the best outcome, seek treatment for a spider bite within 24 hours of being bitten.