Were You Bitten by a Brown Recluse Spider?

Brown Recluse Bites Are Rare

Br-recluse-guy/Wikimedia Commons

The brown recluse spider is known to have a seriously venomous bite. Though the bite is extremely rare, it is responsible for a condition called loxoscelism. This is the only known cause of necrotic arachnidism (tissue death from a spider) and derives its name from the Loxosceles genus to which all recluse spiders belong.

But how do you know if it really was a brown recluse that bit you? This is a very common question because there is a lot of anxiety and fear surrounding the brown recluse.

Capturing the spider responsible will certainly help you identify it, just try not to put yourself in danger of another bite to do so.

Many of your fears can be put to rest with a little understanding of the brown recluse. For instance, these spiders only live in certain parts of the United States and death from a bite is very rare. Also, keep in mind that not all skin boils and necrotic (dead) tissues are caused by brown recluse bites or even spider bites, for that matter. 

Do You Live Where Brown Recluses Do?

Recluse spiders are called recluse because they do not like to be seen. These nocturnal creatures will not attack people unless they're provoked. The majority of brown recluse bites occur because the spider ended up in the person's clothing.

With that knowledge, where you live is actually the first clue on whether or not you've been bitten by a brown recluse. This particular species is found only in the south-central United States.

In one study, researchers from the Department of Entomology at the University of California, Riverside invited people to send them spider specimens they believed to be brown recluses. Out of a total of 1,773 arachnids submitted from 49 states, 158 different species were identified. From those 29 states where brown recluses are not common, only 2 brown recluse specimens were identified.

This study found that if you get bitten outside of where brown recluse spiders are known to live, the chances that it came from a brown recluse are nearly zero. It is more likely that the injury was caused by any number of other things, possibly even another species of spider that is less venomous.

For instance, if you were bitten in northern California or Maine, there's almost no chance it's from a brown recluse unless you recently returned from Mississippi. The bottom line is that we can rule out the brown recluse if you aren't in the areas where brown recluses are known to live.

Was It a Brown Recluse?

Assuming you're in the territory of the brown recluse, it is best if you were able to see the spider that bit you. However, many people do not even realize when they are bitten, so sightings are rare.

If you were, by chance, able to capture the spider that bit you, that is even better. Classifying it is difficult and only an arachnologist (spider expert) can accurately identify a brown recluse for you. It's probably beyond the expertise of your doctor as well, though you should see him anyway if the bite worsens.

While you and your doctor may not be able to identify the brown recluse, there are a few indicators that you have a spider that is at least in the recluse family.

If you can safely observe it, here's what to look for:

  • A recluse will have six eyes set in three pairs called dyads. One dyad will be up front and the others on either side of the head. Most spiders have eight eyes.
  • The furry abdomen (the larger section) will have fine hairs and be a solid color.
  • The legs are one solid, light color and have no spines.
  • The body (without the legs) is not more than 3/8-inch long.

Brown recluses are also called violin spiders or fiddlebacks. These names refer to a violin-shaped mark on the spider's back. However, it's not always obvious on brown recluses and it shows up on other species as well.

Look for the other identifying information instead of relying on the violin.

The problem is that it's more than likely you didn't even feel the bite. In most cases of loxoscelism, the bite is identified by symptoms several hours or days after the fact.

Symptoms of a Brown Recluse Bite

Most brown recluse bites either don't have any symptoms at all or there is a little swelling with a red bump. Some bites will develop a boil or a pimple. These may be completely indistinguishable from an ingrown hair or a skin infection like staphylococcus or streptococcus.

One extensive review of spider bites notes that tissue death around the bite location can spread within a few days. You might notice skin that is red near the center or boil, turning white, then blue as it spreads.

Some of the worst brown recluse bites can lead to necrotic arachnidism, which looks like an open wound that doctors often call ulcers. The term necrotic arachnidism literally means tissue death by means of a spider bite.

It's important to remember that skin infections can lead to necrotic ulcers which look similar to those caused by brown recluse bites. The difference is that necrotic skin infections can be much more dangerous and treatment with antibiotics is possible, so it's very important you see a doctor.

On the other hand, antibiotics do not work for brown recluse bites and there are very few confirmed deaths from loxoscelism. A study published in 2017 looked at loxoscelism cases ranging from 1995 through 2005. Of the 57 reported cases of moderate to severe loxoscelism, only two resulted in death. Both individuals—an older man and a young girl—were healthy prior to the bite.

It should also be noted that the study found 373 possible cases of loxoscelism over that 20 year period. The majority resulted in only minor symptoms that cleared up within a few weeks.

Treatment for a Brown Recluse Bite

Most brown recluse bites heal just fine without any medical intervention or first aid. If you see it happen or suspect that you were bitten, the recommended treatment is to use the common first aid technique called RICE (Rest, Ice, Compression, and Elevation). Wrap the area of the bite with a compression bandage, use ice on it, and elevate it.

If the bite develops into a boil or an ulcer, see a doctor. This typically is not an emergency situation, but you should have a physician take a look. The doctor might take a swab from the boil and culture it to test for bacteria. This helps him know if it can be treated with antibiotics and aids in determining the real cause, spider bite or not.

If you didn't see and feel the spider bite you, then there's really no way to know if it's a brown recluse bite. In that case, it's important to see a doctor for any boil or red, raised area that gets worse, especially if it feels hot and hard.

A Word From Verywell

Though you may be tempted to worry, rest assured that brown recluse bites are very rare. Follow the recommendation of RICE for first aid and monitor the area you think is a bite. If you notice anything unusual or boils appear, see your doctor. With a little diligence, you will be fine.

Source:

Rahmani F, et al. Poisonous Spiders: Bites, Symptoms, and Treatment; An Educational Review. Emergency. 2014;2(2):54-58.

Robinson JR, et al. Defining the Complex Phenotype of Severe Systemic Loxoscelism Using a Large Electronic Heath Record Cohort. PLoS One. 2017;12(4):e0174941.

Vetter, RS. Arachnids submitted as suspected brown recluse spiders (Araneae: Sicariidae): Loxosceles spiders are virtually restricted to their known distributions but are perceived to exist throughout the United States. Journal of Medical Entomology. 2005;42(4):512-521.

Vetter RS. Brown Recluses. University of California, Riverside. 2009.

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