clock menu more-arrow no yes

Filed under:

Stop blaming brown recluse spiders for your horrifying flesh wounds

New, 33 comments

Take comfort, there are plenty of other things that can cause rotting skin lesions

Video of a brown recluse spider by University of California, Riverside and Richard Vetter

That weird, swollen, oozing bump you’re worried about? It’s not a bite from a brown recluse spider, a bug scientist and skin doctors say in an article aimed at combating misdiagnoses. For starters, brown recluse bites are usually flat, pale at the center, and don’t really ooze — unless they’re on your eyelid or toes, that is.

The problem is that brown recluse bites are so attention grabbing that even doctors can see them when they’re not there. So other types of bites, bacterial infections, or fungal infections can be overlooked, leading to potentially dangerous misdiagnoses. This even happens in states where these spiders don’t live, according to an opinion article published today in the journal JAMA Dermatology.

And, really, as I remind myself when I’m trying to fall asleep, the world is full of things that can kill you, or at least, that can cause alarming skin lesions. So the three authors of the article pooled their collective 50 years of experience with spider bites to create a mnemonic to help clinicians out — and give patients a longer list of things to worry about. The mnemonic even hints at the likely diagnosis — NOT RECLUSE. Here’s how it goes:

Numerous

Recluses usually bite once in self-defense, then scuttle off. So if a patient has multiple rotting skin wounds, then it’s more likely to be a bacterial infection, bites from insects like bedbugs or fleas, a reaction to poison ivy, an autoinflammatory disease, or shingles.

Occurrence

Did you get the bite digging through the attic or garage, reaching into an old box, or sorting through a pile of laundry you left on the floor? Or notice the bite after getting out of bed in the morning? Okay, then it might be a recluse.

Timing

Brown recluses are usually active between April and October, so people in North America are usually bitten in that window. Rarely, people are bitten when reaching into boxes of holiday decorations in the winter.

Red center

Brown recluse venom destroys the tiny blood vessels in skin, so the center of the bite is actually pale, sometimes in shades of blue or purple. The surrounding area swells and gets red though. So if the center of the lesion is red, then it’s more likely another arachnid or insect’s bite or sting, or caused by a bacterial infection — by something like strep or, possibly, anthrax.

Elevated

Brown recluse bites don’t bump up — in fact, they sometimes create craters in the skin. So if it’s bumpy, not a recluse (unless it’s on your face — see “Swollen”).

Chronic

Recluse bites usually heal within a few months, so if that skin ulcer is just not going away it could be something even more concerning — like a rare autoinflammatory disease, or a type of skin cancer.

Large

If there’s more than 10 centimeters of rotting flesh, it’s probably not a brown recluse bite.

Ulcerates too early

If it starts crusting over earlier than a week or two after the lesion first appears, it’s probably something else — like, possibly, anthrax. Which is not comforting.

Swollen

Unless it’s on your face or your feet, the bites tend not to swell.

Exudative

Exudative means leaky, in medical parlance. And, according to the authors of this horrifying mnemonic, recluse bites tend not to ooze fluids or pus — unless they’re on your eyelids or toes. So pus usually rules out a recluse bite.

If your oozing flesh wound doesn’t fit two or more of those criteria, then it’s probably not a recluse bite. So, think outside the brown recluse's box. Get creative. There’s always something more horrifying out there. And please, please see your doctor.