First Aid Bites & Stings Print Spider Bite Pictures By Rod Brouhard, EMT-P Updated July 05, 2019 Medically reviewed by a board-certified physician More in First Aid Bites & Stings Allergies & Anaphylaxis Breathing Emergencies Broken Bones Bruises, Cuts & Punctures Heat & Cold Exposure Infections Rash Emergency Preparedness Calling for Help View All It's easy to look at pictures of red, bumpy lesions on the internet—that other people have tagged as spider bites—and think, "that's what I have!" The problem is that many images are misidentified as spider bites by websites, patients, and even doctors. They might be from spiders, but they can also be from other types of bugs or infections. The pictures below show different types of lesions that are often identified as spider bites. Each one is discussed on how it could—or could not—be from a spider. There are only two medically significant spider species in North America: the black widow and the brown recluse. Black widow bites, for example, are very difficult to diagnose by looking at the site of the bite, unless it includes fang marks (see below). It's easier to say definitively when a lesion is not a brown recluse bite than when it is. Bottom line: Without catching a spider in the act, there might not be an accurate diagnosis. Nevertheless, whether it's a spider or another kind of bug bite, treatment is generally the same. Expanding Lesions Chad Warren An expanding lesion, like the one in the picture, is common in brown recluse bites, but there are many other possibilities to consider. Some skin infections can lead to lesions like this. The only way to tell for sure is to have it evaluated by a medical professional. Bullseyes Jake from Atlanta One of the things that set bites apart—whether from spiders or other bugs— from infections is the "bullseye" pattern of discoloration. It shows up as concentric rings of discoloration. It's common in tick bites, especially those that later turn into Lyme disease, and can also be present for spiders. Ticks, scorpions, and spiders are all arachnids. Fang Marks Exodog Black widows have fangs, almost like miniature snakes. Soon after a black widow spider bites you—before any reaction starts—you might be able to see two small holes like those in this image. Black widow venom can cause muscle spasms and heart disturbances, but if you have a black widow spider bite, rest assured that they are rarely fatal. The most common symptoms after a bite (besides the pain of the bite itself) are: Abdominal painMuscle cramps/sorenessSoreness and redness around the biteIrritability/agitation High blood pressure is also common from black widow spider bites, although it rarely causes any problems for the patient. Most of the symptoms are treated individually. An antivenin (spider poison antidote) is available for black widow spider venom, but it's not really necessary for most patients. Classic Recluse Spider Bite CDC Brown recluse bites can go unnoticed, or they can lead to severe pain 2 to 8 hours after the bite. In some cases, patients report feeling a "pinprick" at the site of the spider bite. In true cases of loxoscelism (medical terminology for the condition caused by brown recluse bites), skin tissue that develops could take several months to fully heal and the scars may remain. Generally, brown recluse bites are much less likely to cause significant injury than black widows. Your Spider Bite Might Not Be a Bite at All It's nearly impossible to say for sure if a spider bite comes from a brown recluse without the use of a lab test. However, there are some telltale signs that can be used to rule out the possibility of a brown recluse bite. Signs It's Not a Recluse Bite NOT RECLUSE is an acronym for the signs that a wound or lesion is not caused by a brown recluse bite. It stands for:NumerousOccurrenceTimingRed centerChronicLargeUlcerates too earlySwollenExudes moisture The presence of any of these is an indicator that the wound isn't from a brown recluse. The presence of two or more of these signs almost guarantees that it's not. Let's take a look at each one. How to Tell If You Were Bitten by a Brown Recluse Spider Lots of Lesions Are Not Spider Bites T. Critchley Multiple bites are not typically from spiders, especially not a brown recluse or black widow. In cases with so many bites, consider bugs that travel in groups, like mosquitoes, bedbugs, or chiggers, for example. How It Happens Makes a Difference In order to be a brown recluse bite, the way the bite happened is very important to the story. If the bite occurred because the patient disturbed a spider by moving old boxes in the attic, that's much more likely than getting a bite in the yard. Recluse spiders have that name for a reason; they don't like crowds. They hide in really out of the way, dark places. Bad luck in the backyard, for example, could be due to poison ivy or spiders. It could also be a result of chiggers, which like to get into boots and socks to bite their prey. When it happens matters, too. If a bite doesn't happen from April to October, the chance that it's from a brown recluse are slim to none. Brown recluses are notoriously inactive during the rest of the year. Red, Inflamed Centers Point to Infection Danielle from Binghamton, NY A red, inflamed center is not an indicator of a brown recluse bite. Loxoscelism (brown recluse envenomation) is known for having a dark, flat center. A swollen, hot area can easily be a staph infection. There is a possibility that it's a bug bite, but skin infections are even more likely. Lest you think that staph infections can be the result of a spider bite, it's probably not the case. At least one study found that spiders do not regularly carry bacterial infections. Long Time to Heal Angela Phillips If it takes a really long time for the lesion to heal, it might not be a brown recluse bite. They've got a reputation for lasting a while, but most brown recluse bites heal within three weeks and the biggest of them heal within three months. A line drawn around the lesion, as shown in the picture, is a common method for keeping track of an expanding rash or area of swelling. Be sure to note the time and date when a line is drawn to know how fast the lesion expands. Massive Sores Ivonne H. Brown recluse bites are known for having necrosis (dead tissue) in the center of the lesion. However, the necrosis is not going to be bigger than 10 centimeters across (four inches). A lot of infected sores are identified—even diagnosed—as spider bites. In truth, unless you have a spider to identify as the culprit, the odds are against a spider bite. It's much more likely that a non-spider bug did the biting in this case. If the lesion grows or continues to get worse over a 24 hour period, it's worth taking a trip to see the doctor. If not, it's probably fine just to keep it clean and keep an eye on it. How Skin Infections Are Sometimes Misdiagnosed as Spider Bites Ulceration Nick from Alabama A brown recluse bite will eventually break the skin (ulcerate), but if it happens before the week is out, it's probably not a brown recluse. Sometimes, it's not really obvious that the lesion ulcerated, other than the fact that it develops a crust. So, if it's bleeding or crusty and it hasn't been a week, it's probably something other than a brown recluse bite. Swelling CDC Swelling typically indicates something other than a brown recluse bite. Below the neck, brown recluse bites do not result in significant swelling. Above the neck is a different story. Bites on the eyelids and other very soft tissues of the face often swell after a recluse bite. Any bug bite can lead to swelling from allergic reaction or envenomation. Oozing (c) Gary Goode Brown recluse bites are known for being dry in the center. If it's oozing pus or moisture, it's very unlikely to be a brown recluse bite. Spider Bites: Symptoms, Treatment & Identification Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Email Address Sign Up There was an error. Please try again. Thank you, , for signing up. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Forks TP. Brown recluse spider bites. J Am Board Fam Pract. 2000;13(6):415-23. Savely VR, Stricker RB. Morgellons disease: Analysis of a population with clinically confirmed microscopic subcutaneous fibers of unknown etiology. Clin Cosmet Investig Dermatol. 2010;3:67-78. Cordeiro FA, Amorim FG, Anjolette FA, Arantes EC. Arachnids of medical importance in Brazil: main active compounds present in scorpion and spider venoms and tick saliva. J Venom Anim Toxins Incl Trop Dis. 2015;21:24. doi:10.1186/s40409-015-0028-5 Rahmani F, Banan khojasteh SM, Ebrahimi bakhtavar H, Rahmani F, Shahsavari nia K, Faridaalaee G. Poisonous Spiders: Bites, Symptoms, and Treatment; an Educational Review. Emerg (Tehran). 2014;2(2):54-8. Payne KS, Schilli K, Meier K, et al. Extreme pain from brown recluse spider bites: model for cytokine-driven pain. JAMA Dermatol. 2014;150(11):1205-8. doi:10.1001/jamadermatol.2014.605 Rader RK, Stoecker WV, Malters JM, Marr MT, Dyer JA. Seasonality of brown recluse populations is reflected by numbers of brown recluse envenomations. Toxicon. 2012;60(1):1-3. doi:10.1016/j.toxicon.2012.03.012 Mikkelsen J, Schmidt G, Holmgaard R. Reconstructive considerations following a necrotic spider bite on the face: A case report. Int J Surg Case Rep. 2017;32:76-79. doi:10.1016/j.ijscr.2017.02.023 Additional Reading Murphy, C., Hong, J., & Beuhler, M. (2011). Anaphylaxis with Latrodectus Antivenin Resulting in Cardiac Arrest. Journal Of Medical Toxicology, 7(4), 317-321. doi:10.1007/s13181-011-0183-1 Rader, R., Stoecker, W., Malters, J., Marr, M., & Dyer, J. (2012). Seasonality of brown recluse populations is reflected by numbers of brown recluse envenomations. Toxicon, 60(1), 1-3. doi:10.1016/j.toxicon.2012.03.012 Vetter RS1, Swanson DL2, Weinstein SA3, White J3. Do spiders vector bacteria during bites? The evidence indicates otherwise. Toxicon. 2015 Jan;93:171-4. doi: 10.1016/j.toxicon.2014.11.229. Epub 2014 Nov 21.