When Is A Spider Bite An Emergency?

Spider Bite

Is this your child’s symptom?

  • Bite from a spider

Symptoms of a Spider Bite

  • Most spider bites cause local pain, redness and swelling. It’s much like a bee sting reaction.
  • A few spiders (such as the Black Widow) can cause a more severe reaction.
  • Helpful if spider seen on the skin or around the child

Cause of Spider Bite Reactions

  • Most spiders have tiny fangs. They inject venom into the skin.
  • The venom is what causes all the symptoms.

Types of Spider Bites

Black Widow Spider Bite

  • A shiny, jet-black spider with long legs (total size 1 inch or 25 mm).
  • A red (or orange) hourglass-shaped marking on its under-side.
  • Causes immediate local pain and swelling.
  • Sometimes, you can see 2 fang marks at the bite site.
  • Severe muscle cramps (especially stomach cramps) occur within 1 to 6 hours. These last 24 to 48 hours.
  • Rarely causes death. Exception: bitten by several spiders or small child is bitten.
  • Note: many are dry bites because the fangs are small.
  • The brown widow spider is related to the black widow. It is found in southern US.
  • Brown widow spider bites are treated the same as black widow bites.

Brown Recluse Spider Bite

  • A brown spider with long legs (total size ½ inch or 12 mm).
  • A dark violin shaped marking on top of its head.
  • Causes pain at the bite. Blisters form within 4 to 8 hours.
  • The center becomes bluish and depressed (crater-like) over 2 to 3 days.
  • Skin damage may require skin grafting in 10% of cases.
  • Other symptoms such as fever, vomiting, muscle pain can occur. No life-threatening symptoms occur.
  • Brown recluse spiders are hard to identify. If you can, bring the spider along in a jar.

Non-dangerous Spider Bites

  • More than 50 spiders in the U.S. have venom. Their bites cause reactions that are not serious. This includes pain or redness at the bite site.
  • The bites are painful and swollen. This lasts for 1 or 2 days. They can feel and look like a bee sting.
  • Some single, unexplained, tender bites that occur during the night are due to spiders.

When to Call for Spider Bite

Call 911 Now

  • Trouble breathing or wheezing
  • Passed out (fainted) or too weak to stand
  • You think your child has a life-threatening emergency

Call Doctor or Seek Care Now

  • Fever and bite looks infected (spreading redness)
  • Your child looks or acts very sick
  • You think your child needs to be seen, and the problem is urgent

Contact Doctor Within 24 Hours

  • New redness starts more than 24 hours after the bite. Note: any redness in the first 24 hours is due to venom.
  • More than 48 hours since the bite and redness now getting larger
  • Bite starts to look bad (such as skin damage, blister or purple color)
  • Bite pain lasts more than 2 days
  • You think your child needs to be seen, but the problem is not urgent

Contact Doctor During Office Hours

  • You have other questions or concerns

Self Care at Home

  • Non-serious spider bite

Seattle Children’s Urgent Care Locations

If your child’s illness or injury is life-threatening, call 911.

  • Bellevue
  • Everett
  • Federal Way
  • Seattle

Care Advice for Non-dangerous Spider Bites

  1. What You Should Know About Spider Bites:
    • Most spider bites look and feel like a bee sting.
    • The main symptoms are pain and redness.
    • Here is some care advice that should help.
  2. Clean the Bite:
    • Wash the bite well with soap and water.
  3. Cold Pack for Pain:
    • For pain or swelling, use a cold pack. You can also use ice wrapped in a wet cloth.
    • Put it on the bite for 20 minutes.
  4. Pain Medicine:
    • To help with the pain, give an acetaminophen product (such as Tylenol).
    • Another choice is an ibuprofen product (such as Advil).
    • Use as needed.
  5. What to Expect:
    • The swelling and pain lasts for 1 to 2 days.
    • It should not be any worse than a bee sting.
  6. Call Your Doctor If:
    • Severe bite pain lasts more than 2 hours after pain medicine
    • Stomach pains or muscle cramps occur
    • Bite pain lasts more than 2 days (48 hours)
    • Bite starts to look infected
    • You think your child needs to be seen
    • Your child becomes worse
See also:  What Type Of Spider Is This Uk?

And remember, contact your doctor if your child develops any of the ‘Call Your Doctor’ symptoms.

Disclaimer: this health information is for educational purposes only. You, the reader, assume full responsibility for how you choose to use it.

Last Reviewed: 06/09/2020

Last Revised: 03/21/2020

Copyright 2000-2020 Schmitt Pediatric Guidelines LLC.

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    When to See a Doctor for a Spider Bite

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    Most spider bites are harmless. In fact, people usually don’t even notice when they’ve been bitten. Spider bite symptoms can be so subtle and non-specific—a red, inflamed bump that may be itchy—that it’s often difficult to determine whether the person was bitten by a spider or not. However, the bites of some spiders, including the black widow and brown recluse, can be deadly.

    Types of Spider Bites

    For health purposes, spider bites can be classified into two primary categories: poisonous spider bites and non-poisonous spider bites.

    The vast majority of spiders in the United States are not poisonous. The bites of these spiders are harmless, although they can trigger an allergic reaction or become infected.

    The two poisonous spiders that live in the United States are the black widow spider and brown recluse spider. Black widow spider bites tend to cause pain and cramping that usually start near the bite and spread throughout the body. Other black widow spider bite symptoms include nausea, vomiting, severe abdominal cramping, chills, fever and headache.

    A brown recluse bite may seem asymptomatic at first. However, the affected area usually becomes sore within 8 hours, and in some cases, the center of the bite swells, darkens, blisters and turns into an open sore over a week or so. Other symptoms of a brown recluse spider bite include nausea, fever, chills and rash.

    Spider Bite Treatment at Home

    Most spider bites will heal without treatment. To prevention infection and increase comfort, you can:

    • Wash the affected area with soap and water.
    • Apply an ice pack or cool compress to decrease swelling and ease pain.
    • Consider over-the-counter (OTC) medication. If pain is interfering with activity or sleep, you can take acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) as directed on the packaging. An OTC antihistamine, such as diphenhydramine (Benadryl), can decrease itching.

    When to See a Doctor for a Spider Bite

    Go immediately to the nearest emergency room if you suspect the bite is due to a black widow or brown recluse spider. (Black widow spiders are found throughout the United States and feature an orange-red hourglass on their underbellies. Brown recluse spiders typically hide in dark, quiet places like wood piles and attics.) The bites of black widow and brown recluse spiders can be so serious that it’s important to get immediate medical attention, even if the affected person seems fine.

    An allergic reaction to a spider bite is another reason to seek medical care. Minor swelling at the site of a bite isn’t cause for the concern, but if the swelling seems to be spreading, it’s time to call a doctor. Call 911 if the affected person is having trouble breathing.

    Occasionally, an infection will develop at the site of a spider bite. If the bite looks worse rather than better as time goes on, or you notice pus and increased swelling, call your healthcare provider.

    Who to See for a Spider Bite

    Your primary care provider can handle most allergic reactions and infected spider bites. Emergency department personnel are best equipped to handle poisonous spider bites.

    Most spider bites won’t cause any serious health problems. However, it’s important to pay attention to symptoms and seek medical care as needed. When in doubt, consult your doctor.

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    What Are Spider Bites?

    Symptoms, Treatment & Identification

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    Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.

    Michael Menna, DO, is board-certified in emergency medicine. He is an attending emergency medicine physician at White Plains Hospital in White Plains, New York and also works at an urgent care center and a telemedicine company that provides care to patients across the country.

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    Let’s get this out of the way: That red bump is probably not a spider bite. Odds are, it’s a skin infection. The most common bacterial infections are either Staphylococcus aureus or Streptococcus pyogenes. Both of those create red bumps that get hot, swollen, and spread out.

    If it is a spider bite and you got it in the United States, it’s very unlikely that you will die from it. Of all the spiders in North America, only two are medically significant (capable of actually making you sick): the black widow and the brown recluse.  

    Spider Bite Symptoms

    If you didn’t see the spider bite you, then the chance that it’s an actual spider bite is pretty slim. It’s almost impossible to identify a spider bite just by how it looks.

    Local reactions to bites from all kinds of toxic bugs look the same: redness, swelling, itching, and pain. Be concerned if a local reaction continues to get worse for more than 24 hours. Look for redness spreading away from the bite, drainage from the bite, increase in pain, numbness/tingling, or a discoloration around the bite that looks like a halo or a bullseye.

    Black Widow Spider Bites

    In the United States, black widow spiders are considered the most venomous. They have a toxin capable of a systemic reaction that affects muscle and nerve function.   Black widow spider bite symptoms can be used to diagnose these bites and include:  

    • «Fang» marks (tiny twin holes): telltale signs that are only visible right after the bite happens, before any swelling or redness occurs
    • Sweating
    • Chills
    • Headache
    • Dizziness
    • Muscular cramps (legs, stomach, etc.)
    • Rapid pulse
    • Exhaustion

    Other countries have a widow spider called the redback spider. It’s a good idea to consider any shiny black spider with a red mark to be in the widow family. Another type of widow spider, the brown widow, generally has a weaker toxin and can be found worldwide.

    Brown Recluse Spider Bites

    Despite the terrible wounds often associated with brown recluse, they are much less likely to cause significant injury than black widows. Skin infections may cause boils, which are often misdiagnosed as brown recluse spider bites (take a look at spider bite pictures to help you tell the difference).

    It’s easier to figure out when a bite is not from a recluse than when it is. One tool to rule out brown recluse bites is to use the mnemonic NOT RECLUSE. This mnemonic helps point out things that are not present in brown recluse bites.  

    • Numerous: If there are more lesions than just one or two, they’re not from a brown recluse. Brown recluse bites come in ones and sometimes two.
    • Occurrence: The way that a brown recluse bite usually occurs is through disturbing the spider. Most of the time it’s hidden away in a closet or an attic, possibly in boxes. Occasionally, the spider can find its way into the bed and bite the patient in his or her sleep. If the occurrence was during gardening, it’s probably not a brown recluse bite.
    • Timing: If the bite didn’t show up from April to October, it’s very unlikely that it’s a brown recluse bite.
    • Red center: Brown recluse bites are almost never red and inflamed in the center of the lesion. Usually, they’re pale, blue, or purple. They can be red around the periphery, but if it’s red in the center, it’s probably not a brown recluse.
    • Chronic: It takes 3 weeks for a small bite to heal or 3 months for a bigger bite.
    • Large: The biggest recluse lesions (the tissue that’s dying) have been documented to be smaller than 10 centimeters across (four inches). They can be red and swollen well past that area, but the necrosis won’t be any bigger.
    • Ulcerates too early: For non-medical folks, this one might be hard to remember. Brown recluse bites take at least a week to ulcerate (break the skin and crust over). If it’s crusty before seven days, it’s probably not a brown recluse bite.
    • Swollen: Brown recluse bites are flat or sunken in the middle, not swollen. If it’s swollen (especially if it’s red), it’s not a brown recluse. The exceptions to this rule are bites on the face, especially the eyelids. Those swell significantly.
    • Exudes moisture: Brown recluse bites are dry, not moist. If it has pus oozing out of it, it’s an infection rather than a spider bite.
    See also:  What Is The Scientific Name Of A Spider?

    Brown recluse spiders are only found in the Southeast United States and are very difficult to identify, even by trained arachnologists.   There are several other species of recluse spider that are similar but less studied than the brown recluse. Brown recluse spiders are often described as having a violin-shaped mark on the back of their midsections, but that mark can be inconsistent and very faint.  


    Almost all spiders are venomous. That’s how they hunt. Most spiders are too small, or their venom too weak, to be dangerous to humans. Some spiders are pretty well-known and seem to get blamed for most of the spider bites out there, even though there’s no evidence to support that those lesions are even from spiders.

    Black widow and brown recluse spider bites are those that are most likely to be medically significant in North America. There are more than 40,000 species of spider in the world.   Here are some North American spiders that get a bad rap without much evidence to support their reputations:

    • Hobo Spiders(Tegenaria agrestis): These guys were introduced into the Northwest United States from Europe in the 1980s. Since then, they’ve been blamed for instances of necrotic arachnidism, medical jargon for tissue death by spider envenomation. A study published in the Journal of Medical Entomology in 2011 found no medical significance from hobo spider envenomation.  
    • Wolf Spiders(Lycosidae): Originally from Australia, wolf spiders are commonly thought to be very dangerous. On the contrary, case presentations of presumed wolf spider bites in the United States have reported nothing significant.   A study of 45 definite wolf spider bites in Australia showed that they «cause minor effects, no more severe than most other spiders.» Wolf spiders didn’t cause necrosis-like the brown recluse and most of the damage was mechanical, not from venom.

    Other parts of the world have much more dangerous species than the United States. Australia has the redback spider (similar to a black widow), white tail spiders, and deadly funnel-web spiders.


    Determining whether a bite is from a spider may be impossible. Patients rarely bring the brown recluse spider to an expert, which is required for a proper diagnosis.   Black widow bites are often identified only by symptoms of its venom, without any visible local bite.

    Call a doctor or go to the emergency department if your spider bite symptoms persist more than 24 hours or get worse, or if you think it’s a brown recluse or black widow. You should also call a doctor if you are not up to date on your tetanus vaccination.

    If you go to the doctor for a reaction, don’t start out by telling him or her it’s a spider bite—even if you think that’s what it is. Doctors are people, too, and they are susceptible to the power of suggestion just like the rest of us. Instead, tell the doctor, «I have this rash (bump, boil, red spot, black spot, etc.) and I was wondering if you could tell me what it is and what I can do for it.»

    Plenty of skin rashes and sores get diagnosed in the emergency department as spider bites, but the reality is that most are not. One case study of an outbreak of bites in military barracks—at least what authorities thought were bites—turned out to be MRSA.   All the more reason to be skeptical of a diagnosis of spider bite in the emergency department.

    Skin boils from infections are often mistaken for spider bites in the United States, even by doctors.


    You can treat all bug bites the same unless it’s a brown recluse or a black widow bite. Some articles on the internet tell you to treat venomous spider bites differently than non-venomous bites, but as you’ll see, there’s no such thing as a non-venomous spider bite.

    There are many home remedies for treating insect and spider bites, but do they help? Most of these have not been shown to provide any real benefit. Meat tenderizer (papain) has even been implicated in allergies and asthma reactions to its protein. Suction syringes that are sold to extract toxins do not work and are a complete waste of money.

    Allergic Reactions to Spider Bites

    Anaphylaxis is always the biggest concern with any type of bug bite.   If the victim exhibits any signs of allergic reaction or anaphylaxis shortly after a bug bite, call 911. Other symptoms can include:

    • Hives
    • Shortness of breath
    • Wheezing
    • Weakness

    Seek medical treatment if symptoms appear in parts of the body away from the bite.

    Williams M, Nappe TM. Black Widow Spider Toxicity. StatPearls Publishing. Updated March 8, 2019.

    Livshits Z, Bernstein B, Sorkin LN, Smith SW, Hoffman RS. Wolf spider envenomation. Wilderness Environ Med. 2012;23(1):49-50. doi:10.1016/j.wem.2011.11.010

    Meires J, Louden B. Bite of the Brown Recluse Spider. Clinical Review. 2010(12):14-17.


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