How to Identify a Spider Bite

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This survival-medicine website provides general information, not individual advice. Most scenarios assume the victim cannot get expert medical help. Please see the disclaimer.

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.

  • Fortune Hovind

    I live in michigan and have been bitten 9 times in 9years. I currently have been bitten and believe it happened while i was sleeping, but I never know what kind of spider bit me. i contracted MRSA form the first time I was bitten and am on antibiotics now. How can you tell what kind of spider bit me?

    • http://thesurvivaldoctor.com/ James Hubbard, MD, MPH

      Other than the post? Get some sticky paper and trap one. Also, MRSA can look just like a spider bite.

  • SChil5

    Hi, I have been bitten three times and my ex-boyfriend was bitten twice by a recluse spider. Come to find out they were infesting one of the trees and his back porch area. We found out the trick to preventing these bites from getting really bad is you have to get the hard plug out. It hurts like heck and is best done by a doctor. I squeezed mine out myself. I know it sounds gross, but that is where most of the venom is – deep down in that plug and that is where everything spreads out from. Once we got the plugs out, the bites started healing right away. Just don’t wait too long. Most doctors don’t know how to treat recluse bites. I live in Texas and we found a good old Texas doc that had treated many of these and he is the one who finally told us what needed to be done. He lanced my boyfriend’s bite and got the plug out and a lot of poison. gave him a good antibiotic and in a few days we could already see the difference. I’m telling you — you need to cut it open and get that plug out and preferably do it in a doctor’s office. But you have to convince them that is what to do, as most of these young doctors haven’t a clue about treating brown recluse bites.

  • Sarah Labrecque

    I got a bite five days ago two marks hurt for a few hours then nothing till today.. Now puffing up red hot.. Live in NC. Can it take this long for a brown recluse to start symptoms?

    • http://thesurvivaldoctor.com/ James Hubbard, MD, MPH

      Not that I know of. Perhaps the wound is getting infected.

  • flamegirl

    I live in the uk and think I may have been bitten by a spider. I felt really sick on monday with a fever, dizziness and severe muscle cramps and have an itchy bite in a raised red welt on my leg. By tuesday I felt pretty much ok but still a little dizzy and naseous. It is now thursday and I still feel the same. Could my illness have been caused by the bite and is it worth going to the doctor?

    • wersdon

      Hiya just asking how you got on with your spider bite…. i am in uk and was bit 5 days ago by a little black spider and have been feeling unwell like you did still feel spaced out on antibiotics just hope they work but finger still very sore throbbing and a pin prick feeling there also my throat felt dry like i couldnt swallow and glands were raised sore just carnt believe id feel so unwell so just wondering how you got on with your bite… with thanks xxx

    • http://thesurvivaldoctor.com/ James Hubbard, MD, MPH

      If you’re still having symptoms, you should see a doctor.

  • fivegoofs

    Two weeks ago I had a massage, and the next morning I woke up with an extremely sore hand all around my thumb. I figured it had something to do with the massage. I have been treating it with naproxen and a muscle relaxant, which I have also been taking for back pain. Back pain is not unusual for me, but I have never had pain in my thumb area. It has been a tiny bit swollen the whole time, but nothing alarming. I had another massage today, and she spend a lot of time on my hand and arm, which were both very tight. As I was sitting here typing away, I looked down and saw two tiny dots on my hand, very close to where the worst pain is. They are tender to touch, as is that whole area. I googled spider bite photos, and it looks just like the black widow bites. I live in southern Ontario, Canada, where we are covered in a few feet of snow. We definitely get spiders in our home, but I have never seen one that looks like a black widow. My question is, since this is 2 weeks after my pain started, could it be related? If it is a bite, it affected me in no other way. Do I just keep taking the meds and hope the pain ends soon, or is there still something my doctor could do at this late time? Thanks, in advance.

    • http://thesurvivaldoctor.com/ James Hubbard, MD, MPH

      It’s unlikely that two spots would appear 2 weeks after the bite. However, if it’s been that long and you’re not getting better, you should see a doctor.

  • Bridgette

    I was bit 2 days ago. The bite looks similar to a nipple and is a bit itchy. There is no swelling and the only major symptom is tiredness. I slept most of the weekend away which is very unusual for me and struggling to stay awake today. Any idea what bite it is and how I can treat it?

    • http://thesurvivaldoctor.com/ James Hubbard, MD, MPH

      Bridgette. If you live in the U.S. then all my info is in the post. If it spreads or doesn’t get better, see a doctor. Sometimes, what looks like a spider bite, is actually an area of infection, like MRSA. http://www.thesurvivaldoctor.com/2012/09/18/how-to-treat-mrsa/ If it’s a spider bite, then it, maybe acetaminophen (Tylenol), Advil, or Aleve might help the symptoms.

  • kyrodeogirl23

    Can anyone tell if this is a spider bite and from which one??? There are two separate bite marks if you can see the two blisters. I can’t believe that’s from one spider, or I’m burning this house down, haha. I’m in KY, so we do have Black Widows & Brown Recluse. I also have 5 cats and 4 dogs in here, so I rarely find anything type of bug as they’re my bug soldiers, ha. Thanks for any help.

    • http://thesurvivaldoctor.com/ James Hubbard, MD, MPH

      Can’t tell for sure, but possible. If it’s getting worse, you should see a doctor.

  • Laura Leigh

    I was bit by a brown recluse. It had a big black hole where the bite was. It was on my inner calf and I could not walk. It was terrible and now I have a circle shaped scar where the black hole cent er was. We knew what it was pretty quick. Here where I live in Texas we have tons of them.

    • http://thesurvivaldoctor.com/ James Hubbard, MD, MPH

      Thanks, Laura. Yes, they can do quite a bit of damage sometimes.

  • ryan

    dear hubbard earlier last month I had a spider bite me and it felt a thorn prick on my right foot and it started hurting immediately and I went to my doctor and he said it was a spider bite but was and I live in northern texas and we don’t have hobo spiders down but was it a black widow or a brown recluse………

    • http://thesurvivaldoctor.com/ James Hubbard, MD, MPH

      Ryan, I can’t make a specific diagnosis but hopefully the post can help you decide. Also know that many insects and non-venomous spiders can hurt when they bite you.

  • CPsLove

    Cold potato poultice with about an ounce of the herbs Borage and Plantain, old family remedy.