How to Identify a Spider Bite

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How to Identify a Spider by Its Bite

A black widow spider, with its tell-tale red hourglass. If you feel pain when the spider bites, this is likely the culprit.

by James Hubbard, MD, MPH

I’ve seen a lot of spider bites in my day, and more often than not, the spider is never seen. Over the years I’ve developed several tricks for how to identify the spider by the bite.

There are three types of poisonous spiders in the U.S. The brown recluse is found in the southern two-thirds of the country. It likes to hide in boxes so I often wonder if it doesn’t catch an occasional ride by freight. The hobo spider likes it out west. The black widow has been found in every state but Alaska.

Here are my tips on how to identify a spider bite.

1. Evaluate the Pain

If you feel pain when the spider bites, it’s likely a black widow, whose bite is often but not always painful. You may also develop severe body aches and fever.

A brown recluse spider bite is a slight sting at best. Most of the time you feel nothing. They hide in or under boxes, under your bed sheets, in your clothes. The first you know about it is the pain that develops several minutes to hours after the bite.

A brown recluse spider bite, two months later. This is the eschar—the black, leathery, dead tissue—that can form over the wound. The photographer writes that it was surgically removed about a month after this photo.

A hobo spider’s bite feels similar to a brown recluse’s, and the pain also occurs minutes to hours after the bite.

2. Look at the Skin Damage

That’s the key to the brown recluse spider bite. You may not know when it bit you, but the bite area becomes red, blistered, or black. The area starts out small, and the redness spreads. A black spot of dead tissue develops in the middle of the redness. This dead tissue can be anything from small and superficial to deep and large—sometimes enough to warrant a skin graft when everything’s said and done. As the tissue dies, the area becomes very painful.

The hobo spider can cause skin damage, but less so than the brown recluse.

The black widow spider bite causes a red spot that’s sometimes hard to see. (More obvious: It can cause plenty of muscle aches and cramping throughout the body for one to three weeks.)

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How to Treat a Bite From a Poisonous Spider

If you can get to a doctor, do so. If you can’t, consider the following.

If you think the spider was a brown recluse or hobo:
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  1. Slow the venom’s spread: Apply ice, and keep the area at heart level or above.
  2. Prevent infection. As the black layer of dead skin (eschar) sloughs off, treat the wound as you would any other, by keeping it clean and covered and applying antibiotic ointment or honey. Some large wounds take several weeks to heal. If it starts looking infected, you’ll need oral antibiotics.
  3. Treat the pain. Take an over-the-counter pain reliever.

Some think steroids might decrease the extent of skin damage from a brown recluse bite. Sometimes skin grafts are required when the wounds are too big to heal on their own.

If you think the spider was a black widow take a pain reliever like ibuprofen or acetaminophen for the muscle cramps.

Within minutes to hours, a black widow bite can lead to severe chest and abdominal pain mimicking appendicitis or a heart attack. It can make your blood pressure go up, which may need to be treated. (Possible signs include an increased heart rate and a flushed face.) If you can’t get to a doctor, rest to try to lower the blood pressure. In worst cases, antivenin may be given.

The good news is it’s very rare to die from a spider bite.

Has anyone ever had a brown recluse, hobo, or black widow bite? How did you identify the spider type? What were the symptoms? How was it treated? How are you doing now?

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Black widow photo by Texas AgriLife Extension Service. Photo of brown recluse spider bite by Jeffrey Rowland.

  • Katelyn

    I got bit by a spider but I didn’t realize it until the next morning and even then I thought it was a pimple but it hurt like crazy! Sunday of this week I asked my parents what was happening and they told me it was a spider bite and it hurts to even have a shirt or even something over it or touching it. It has a fever to the bite its red all around. I put a piece of fatback on it last night and it somewhat worked but it is hurting very severely. It is located on my lower right side of my stomach. I really need to know what kind of spider bit me…

    • James Hubbard, MD, MPH

      I couldn’t tell you. Could be a hobo, or just a non-poisonous one that got infected. If the redness continues to spread, ask your parents to check it again to see if you need to go to the doctor for possible antibiotics.

  • Victor III


  • Victor III

    This is about day five, it’s Wednesday and I was bite Saturday night… Should I be worried? It’s gotten a bit worse day by day… Possible that I was scratching it. It doesn’t hurt at all or burn just itches, my leg dose not feel any weaker or sleepy.

    • James Hubbard, MD, MPH

      Do you know what bit you?

  • Jay

    I got bitten by a brown recluse just under a week ago. I didn’t notice until the next morning when I felt some pain and assumed it was just a regular spider bite. The next day I had woken up from the pain, it felt like a bruise and that an iron was being pressed to my skin. The area around the bite had become extremely red and it was about the size of my hand. I went to the doctor and got put on antibiotics, and she had told me that if I waited any longer I would’ve been sent to the hospital. The bite formed into a painful blister, and it popped 5 days later. It’s had an abnormal amount of puss pouring out of it so I had to drain it, then applied polysporin. After the blister was drained the venom had eaten away at my skin and it has left a crater in my skin. It’s still in the healing process so I am hoping it doesn’t scar too bad! :( moral of the story go to the doctor if you’ve been bitten!! This experience has diminished my phobia of doctors that’s for sure. Now the arachnophobia is extremely bad :( everywhere I go I’ve got my eyes open for spiders

    • James Hubbard, MD, MPH

      I wish you the best, Jay.

  • jade napier

    I’m not sure what I was bit by:/ I’m from michigan near detroit. One night when I went to let my dog inside I felt a sting on my arm, almost like a burn. It looked like a hive, then turned into a blister, when that popped, I was like with a hole. Wish I knew what kind of spider and how long it will take to heal. This is about 2-3 weeks after

    • James Hubbard, MD, MPH

      If there’s a hole taking weeks to heat it sounds like a brown recluse bite.

      • jade napier

        Thank you very much for your reply. I am lucky it was not worse . It has gotten alot smaller.i have been cleaning it with peroxide and triple antibiotic ointment. Do you recommend anything else ?

        • James Hubbard, MD, MPH

          Sounds like it’s working since the main thing is try to avoid infection.

    • jade napier

      Darn it won’t let me post a picture

  • TipsyReader

    Any advice on my type of bite ? I’m trying to avoid a trip to the doctors but if it’s necessary I of course wouldn’t mind. It’s located on the bottom of my hairline on the back of my neck and I can’t sleep on my back or move my neck around without feeling pain from the bite. The first 3 days it wasn’t this swollen it started off as a skin colored bump but today it turned red and puffed up

  • Efe

    Please fix this error: spiders are NOT poisonous, they are Venomous creatures.

  • cynthia brennemann

    I was bitten by a brown recluse. I was shelling black walnuts and got one trapped between my pinky finger and the slat basket we were using, so it bit me. I saw it, felt, it, and was able to put the spider in a jar to take to the doctor. When I called for the appointment, they seemed skeptical and gave me an appointment for a week later. I was fairly ignorant about spider bites at the time, but already disenchanted with modern medicine, so I just went and soaked my hand in hot salt water. BIG mistake. Supercharged the venom. I was able to actually SEE the spread of the venom happening. Did some research online, and tossed out the hot water, and replaced it with cold salt water. That did help, but I was a bit nervous about trying anything on my own, and just kept it bandaged till I finally saw the doctor. He verified that it was a brown recluse, examined the, by now very swollen, red, and going necrotic finger, and suggested we amputate. I disagreed. He insisted. I went home, with my finger, and started working at trying to save it. Here’s what worked for me. I made a mix of activated charcoal, bentonite clay, and sea salt, ground fine. When I could not be soaking my hand, I used this as packing in a bandage. When I could soak my hand, I did it in cool to tepid water with alternating mixes of sea salt, Epsom salts, even a capful of bleach, along with tea tree oil, oregano oil, rosemary, lavender oil, grapefruit seed extract, and colloidal silver. I used a sharpie marker to mark round the border of the redness and the border of the white spot and black spot to monitor whether the problem was spreading or receeding. To my relief, as soon as I started doing this regularly, it began receeding…almost imperceptibly at first, and then more noticeably. Because I had supercharged it with heat right off, it probably took longer than it should have to heal, and a year after the bite the area was still a bit red, thin skinned and shiny. As soon as the hole closed up I began using arnica on it (had been using arnica soap all along) and coconut oil. Now, you cannot even see a scar.

    • James Hubbard, MD, MPH

      Thanks for sharing, Cynthia.

  • chili

    I got bit by a spider two days ago. It was a stinging pain and I thought it was just a splinter – I was at a playground with wood chips all over. So I brushed myself off and felt a bug come off my arm. I didn’t think it was a spider at the time because I didn’t see it. When i got home I could see the two red fang marks on my elbow. The red swollen area spread to about apricot size. As soon as I suspected a spider bite, i washed it and made a paste of White vinegar and Baking soda and kept applying that through the next day. When I woke up the next day, I felt tired and my muscles were stiff like I had worked out the day previous. The fang marks were raised up and filled with yellow pus which popped when I put the baking soda and vinegar on. I didn’t think anything about that, but kept applying the baking soda and vinegar paste and took benedryl. I slept all afternoon of that day. When I got up the third day I was still so exhausted for some reason. I had to go to work, so I put neosporin on the bite mark and went to work. All day I felt so tired and exhausted. Maybe from the benedryl but I haven’t ruled out the spider bite just yet. The redness has gone down to a more localized area around the fang marks probably about a quarter size. I haven’t felt any other symptoms other than feeling drained and utterly exhausted. The spider bite is still itchy and the fang marks can still be seen but there is no sign of skin decay. Hopefully the exhaustion will wear off in a couple days as the bite heals.The pictures from left to right are Day 1, Day 2, and Day 3

    • James Hubbard, MD, MPH

      Wish you the best. If you continue to have symptoms, have them checked out.

  • Bethany Rucker

    Woke up with these irritations on my arm and abdomen, they are red, warm and slightly hard. The one on my arm seems to have a line going up my arm along my vein, I’m very concerned. I’m going to see a doctor after work, but I’d like to have your opinion, please and thank you.

    • James Hubbard, MD, MPH

      Sounds like cellulitis. Please let me know what your doctor says.