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.

  • Lisa Nelson

    I don’t know what I got bitten by because I did not see it, however it has itched all day. The picture does not show that well, but there are 2 marks close together, both are raised, and have like little dark spots in the middle. Keep in mind these are very small marks. Should I be concerned? I am not running a fever, but the area around the 2 marks is red.

  • briannaah

    I have a spider bite from 3 days ago , I saw the spider on my but I didn’t think it was a spider , so I left it there …. I saw it was gone 5 minuets later but also when it left I felt the sting , the sting was just barely anything but it itched and itched and itched , but its real puffy and it bleeds alot , and when I take a shower it burns like crazy!! My mom said I’m gonna have to get it lanced but I don’t even know why?!?!? It’s puffy like a centimeter high , but it only itches when I change clothes and when I take a shower , any help?

  • Christine

    Do these resemble spider bites?

    • James Hubbard, MD, MPH

      Christine, sorry, but I don’t try to specifically diagnose without a direct exam. It would nice to know what bit you so you’d know, for instance, if you had something in the house to get rid of but, in general, the bottom line with any bite is what kind of reaction it is causing. If none, such has whelps, infection, fever, skin loss, then keep the area clean. Again, that’s a general statement. If you have specific concerns, have it checked.

  • Brandy Wright

    I was bitten by something two days ago. I never saw it but I was down working in the lawn and it got in my jeans. I didn’t feel the initial bite but for nearly two hours after all I feel was pins and needles or almost like a bunch of bees stinging at once.. even like things crawling on me. It turned red in about a three to four inch circle quickly.. two days later its turning dark in spots. Still burning and hot but the pins and needles effect left. Its very sensitive and the top layer of skin seems to be peeling. Any idea what kind of bite this might be? Tomorrow is day three and it went fromred to turning dark. I know you can’t diagnose but any suggestions? Its not wanting to allow me to upload the photo..

    • James Hubbard, MD, MPH

      Just speculating, it sounds like it could have been a brown recluse. If that were the case, it had to have been in your jeans before you put them on or in a pile of debris. If not, many insects can give you a pretty bad local reaction. If the reaction is bad enough, it could kill some top layers of skin which would slough off. But, as far as I know, only a brown recluse is going to kill deep tissue. If it’s getting worse, you should see a doctor.

  • Teila Smith

    ive been noticing a lot of tiny little spiders around my house lately. never really looked too close at them. somebody thought it would be a good idea to bite me though. i have several tiny little blisters on my inner arm now. although i highly doubt its a brown recluse bite even though they are common here i am putting a mixture of bentonite clay, powdered plantain leaf (the broadleaf herb not the fruit), and powdered echinacea. i hope one day modern medicine institutions will realise and appreciate that sometimes when modern medicine lacks or fails, natural remedies really can be effective (they already do with honey in burn wards). besides i used this treatment on my boyfriend last year when he actually was bit by a recluse and you wouldnt even know it by looking (no necrosis or infection, apparently it stung quite a bit until the clay pulled all the poison out) took several days of treatment (change poultice 3-4x daily) but its better than a shot in the rear of overpriced ER antibiotic and steroids (activated charcoal (only effective the first several hours after the bite), bentonite clay powder, powdered plantain leaf, powdered echinacea a. and p. all cost about $15 from the herb store). youll also want to make tea with the echinacea and drink it about 3 times/day. it acts as an antibiotic and stops secondary infection which is common especially in recluse bites. the other items pull out the toxins and the plantain soothes. the plantain can also be mixed with the echinacea powder to make tea. treat it from both sides. 1/2 teaspoon of each to a cup of boiled water steeped tightly for 10 mins. vit C is also a good idea. as with all herbs please check for contraindications with health issues you may have or pharmaceutical drugs you may take. i would imagine aside from the bentonite clay these herbs could be interchanged with garlic/black elderberry/ tea tree oil (do not take internally) for infection and calendula/lavender/tea tree oil for irritation or any number of other herbs that give the same benefit without risk of allergy/interaction. hope this makes sense and helps

  • Brendette

    let the air bust and dry the wound DONT do it yourself

  • Brendette

    vitamins helped momentarily but allowing air to get to the wound to bust or dry it out is the best still medicating with Benadryl and herbs still sick just trying to keep going because only a few people believe me my husband didn’t see the spiders so he naturally thinks im fine NOT fine and still having to keep my household running really sucks still wish I could show you the pictures don’t have the equipment to load them from my cell phone

  • Brendette

    taking prenatal vitamins seems to be helping rapidly. will see how I feel first thing in the morning but it seems as though I have found what I needed to do. I certainly hope so!!!!!!!!

  • Brendette

    oregano leaves are the only true relief for the intense pain. tried to sleep on those last night. wont do it again. resulted in woosy lightheaded state, but I found that some more of the poison had oozed out on its on with no bruising. night is the worst because the pain intensifies. I am careful to prop up my head and to keep the lavender and Benadryl by my bedside. the lavender keeps my back cool and from me getting fever. have found that the garlic was burning my tongue so now I just smell it. I did too much of that yesterday and my mouth bruised a little. it’s now pink and healthy again. desperate times call for desperate measures, some people say. desperate to not get internal damage or infection. cant wait until this is healing and better…. two words, use Lysol. the Lysol made the sick room smell better. and it gave me piece of mind. kind of comforting sort of hospital smell.. the main reason im not in the ER is because antivenin has a whole new set of risks of its own that I want to avoid if possible. plus it is a risk to get a needle prick. also, the emitted poison stinks like nobody’s business. going to try to at least lie down now. have been quietly sitting in soft chair and medicating and cleaning bedclothes today.

  • Brendette

    how can I know when the poison is neutralized?
    Will I just feel better and stop swelling? mY LAST TIME BITTEN BY SO MANY WAS WHEN I was 10 or 11 and I screamed and passed out. wound up waking up a week later to find I had pneumonia.