When Does A Spider Bite Go Away?
Is It a Spider Bite? Probably Not
- 1 Is It a Spider Bite? Probably Not
- 2 Spider Bites Rare
- 3 How to Know When a Spider Bites and What to Do About It
- 4 Identifying a Spider Bite: What Does One Look Like?
- 5 Spider Bites Usually Heal on Their Own. Here’s When to Seek Medical Attention
- 6 Why Do Spiders Bite People?
- 7 Do You Have A Spider Bite? These 7 Photos Can Help You Tell
Researchers Say Spider Bites Are Overdiagnosed, yet Underappreciated
July 13, 2011 — Spider bites aren’t as common as most people and most doctors think, according to a new analysis.
At the same time, researchers also say poor understanding of truly dangerous spider bites delays treatment when a person really has been bitten by a dangerous spider.
For example, the bite of the brown recluse spider can cause death of a sizeable area of skin (skin necrosis) resulting in a deep, scarring ulcer. Yet even in areas infested with brown recluse spiders, true bites are uncommon.
The analysis is published in the July 14 online issue of The Lancet.
«The treatment of patients with suspected spider bite is not straightforward because of overdiagnosis of skin necrosis as being attributable to spider bites while, at the same time, serious [spider bites] . are not being recognized and treatment is delayed,» write Geoffrey Isbister, MD, of the University of Newcastle, Australia, and Hui Wen Fan, PhD, of Butantan Institute, Sao Paulo, Brazil.
Isbister and Fan note that there are more than 41,000 known species of spider, but that very few have bites harmful to humans.
The names of the two U.S. spiders with harmful bites are well known: the black widow and the brown recluse. The two spiders have different venoms:
- The bite of the black widow may not be very painful at first. Pain onset usually is gradual and usually takes the form of back and belly pain that can last for hours or even days.
- The bite of the brown recluse (and 12 other recluse spiders in North America) can be mild and just cause a mild, itchy bump. But in severe cases, the bite may be painless at first, but over the next two to eight hours develop a sharp, deep pain followed by a burning feeling. The area around the bite reddens and spreads into a deep ulcer that can be as wide as 16 inches across and can take six to eight weeks to heal.
What about other spiders?
«Many additional spiders . have been implicated,» wrote Mayo Clinic dermatologist David L. Swanson, MD, and University of California spider expert Richard S. Vetter, MS, in a 2006 report. «Unfortunately, most of the implicated spiders have been falsely elevated to a status of medical significance through circumstantial implication and repetitive citation in the medical literature.»
Spider Bites Rare
Because of the range of symptoms, people often mistake insect bites, chemical burns, allergic reactions, and skin infections for spider bites. But true spider bites are relatively rare, even in households found to be infested with hundreds of brown recluse spiders.
Unless the brown recluse spider is caught in the act, doctors must be willing to challenge the diagnosis of brown recluse spider bite, Swanson and Vetter note.
It’s a different story in South America, where recluse spider bites are a major health problem. But in the U.S., the spider’s range is from the southern Midwest to the Gulf of Mexico. They’ve been found from southeastern Nebraska through southern Iowa, Illinois, and Indiana to southwestern Ohio, extending south from northwestern Georgia to central Texas. Unless transported, they are not found west of the Rockies.
Extensive searches turn up no brown recluse spiders in the southern third of Georgia and in Florida. But that doesn’t stop people from thinking they’ve been bitten by a brown recluse. No recluse species are native to Florida, yet over a six-year period Florida poison control centers received 844 brown recluse bite reports — 15% of them from medical personnel.
In Georgia, researchers asked people to send them their brown recluse spiders. Some 1,060 people sent in spiders they believed to be brown recluses. Only 19 really were. Most turned out to be harmless Southern house spiders, wolf spiders, or orb weavers. The experts who conducted the study went on a field trip to seek out brown recluse spiders in Georgia; they found none. Yet over that period there were hundreds of reported brown recluse bites.
Brown recluse spiders are not rare in many areas of the U.S. In a 2009 report, Vetter and colleagues noted that a family in Lenexa, Kan., collected 2,055 brown recluse spiders over six months in their home. In an Oklahoma barn, spider hunters found 1,150 brown recluses in just three nights.
Even though the brown recluse is a common house spider in several states, bites are relatively uncommon. For example, the four family members in the Lenexa, Kan., house suffered no bites after eight years in the house.
It’s lucky spider bites are rare, as there’s no definitively proven treatment. While anti-venom exists, there’s no proof it helps — although there’s a long history of safe use, so Isbister and Fan recommend continuing to use it. However, anti-venom probably does not prevent the ulceration and scarring of a severe brown recluse bite.
«Studies are needed to prevent the unnecessary use of ineffective antivenom, which puts patients at risk of allergic reactions,» they suggest.
Isbister, G. and Fan, H.W. The Lancet, published online July 14, 2011.
Vetter, R.S. Journal of Medical Entomology, January 2009; vol 46: pp 15-20.
Swanson, D.L. and Vetter, R.S. Clinics in Dermatology, 2006; vol 24: pp 213-221.
University of California, Riverside Spiders Site.
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How to Know When a Spider Bites and What to Do About It
Medically Reviewed by Ross Radusky, MD
You spot an angry-looking red welt on your leg, and it seems too big to be a mosquito bite. Must be a spider bite, right?
Not so fast. “People wake up in the morning and find a red mark, and immediately call it a spider bite,” says Rick Vetter , a retired staff research associate and entomologist at the University of California, Riverside. But, he says, most of the skin issues people pin on spiders are actually other types of bug bites or skin issues.
Other researchers back Vetter up on this. “Spider bites are really rare,” says Jonathan Day, PhD , a professor of medical entomology at the University of Florida. He explains that most “spider bites” are more likely mosquito bites that were scratched and became infected. “Spider bite is a catchall grouping whenever there’s a severe skin infection; they’re all lumped in as spider bites,” he says.
So the first thing every spider expert in America would like people to know about spider bites is that they’re uncommon and often misdiagnosed. That said, some spiders do bite people, and the result can be ugly.
Identifying a Spider Bite: What Does One Look Like?
A lot of things. “There’s no one true spider bite,” Vetter says.
Spider Bites Can Look Very Different
Different types of spider bites may provoke different reactions in different people, he says. Even if you’re talking about just one type of spider — say, the brown recluse — its bite could cause a range of reactions: “everything from a little pimplelike bump to a rotting-flesh lesion,” he says.
At the same time, Vetter allows that different types of spider bites do produce distinct reactions. “I’ve had patients contact me saying, ‘This mark on my leg was either from a widow or a recluse,’ but that’s like saying you either got stabbed or trampled to death,” he says. His point: Black widow and brown recluse bites are so different that they could never be mistaken for one another.
But when it comes to common household spiders, hobo spiders, and other domestic varieties, a spider’s bite has some predictable characteristics.
How to Identify Which Spider Bit You
Broadly speaking, a spider’s bite tends to resemble a bee sting: a sharp prick of pain is followed by a red, inflamed skin lump that may hurt or itch but that goes away after a few days. (1) But when it comes to venomous spider bites, there are characteristic signs and symptoms.
Brown recluse bites sting, and they can resemble anything from small blisters to large, rotting-flesh sores, Vetter says. “Its bite causes the collapse of the capillary bed”— also known as skin necrosis (2) — «so people who are obese and have poor support of the capillary cells may have a more massive reaction,” he explains. Along with a wide variety of skin symptoms, brown recluse bites can cause chills, fever, nausea, and other flu-like symptoms common to infections. (3) The brown recluse’s bite is poisonous and can result in coma, kidney failure, or even death.
Because of the severe reaction a brown recluse bite can trigger, these spiders are likely blamed for more harm than they actually cause. The reality is that the brown recluse spider is limited in its geographic range: It’s found in the central and southern United States. (4) The Centers for Disease Control and Prevention (CDC) notes that while venomous spiders are dangerous, they aren’t usually aggressive. (2)
Black widow bites can in some cases cause skin lesions, ranging from small red marks to angry, red, streaky skin patches that are inflamed or contain pus. “But most of the reaction will be on the inside,” Vetter says.
Black widow bites contain potentially deadly amounts of venom and tend to be painful right away. Although that pain starts around the bite site, within an hour, it often spreads to the chest or abdomen, depending on whether the bite occurred on the victim’s upper or lower body. Other symptoms can include everything from headaches, muscle weakness, and difficulty breathing, to seizures, numbness, and painful muscle cramps. (5)
Hobo spiders, wolf spiders, house spiders, and the bites of other domestic types do not contain venoms that are of medical importance to humans, Vetter says. They can bite, he adds. But the result is likely to be similar to a bee sting — meaning a sharp pain, followed by a swollen, red, painful lump at the bite site.
Spider Bites Usually Heal on Their Own. Here’s When to Seek Medical Attention
If you think you were bitten by a black widow or brown recluse spider — either because you actually felt and saw the spider, or you’re experiencing the types of skin or systemic symptoms consistent with their bites — head to the emergency room. (6) Vetter says that recluse bites do usually heal on their own and don’t cause scarring wounds. But it’s better to play it safe.
If your spider bite isn’t causing any internal symptoms, or you’re sure it wasn’t a black widow or brown recluse that bit you, follow these steps:
- Clean the bite with soap and water.
- Swab the bite with alcohol to prevent an infection, Dr. Day recommends.
- Apply ice or a cold compress to keep the swelling down.
If pain or itching develops at the bite site, it’s fine to take OTC pain meds or antihistamines for relief. But if pain spreads beyond the site of the bite, or if the swelling, inflammation, or redness are getting worse even a day or two after the bite occurred, get medical attention. You may have a secondary infection — something caused by bacteria getting into the bite — or you may have been bitten by a widow or recluse, Day says.
Why Do Spiders Bite People?
Unlike many other biting bugs, spiders are neither bloodsuckers nor flesh eaters. Vetter says they bite people for one reason only: self-defense.
“Biting is a last-ditch defensive response if a spider is being squashed,” he says. This can happen when someone rolls over in bed on top of a spider — or sits down on one, he says. “I’ve transferred spiders hundreds of times, and they’ll be running all over my arm and have no interest in biting,” he adds.
So while spider bites do occur, they’re far less common than most people assume.
Do You Have A Spider Bite? These 7 Photos Can Help You Tell
And here’s when you should see a doctor.
When it comes to spider bites, there’s literally one person ever for whom it’s been a great experience (what up, Spiderman?). and he’s fictional.
For the rest of us non-superheroes, getting bit by an eight-legged critter is something we’ll do anything to avoid. And with good reason: At best, getting bitten by a spider is an icky, slightly painful experience. But, at worst, it can be a life-threatening nightmare.
The good news: Out of the 3,000 or so types of spiders in the U.S., only a handful are known to bite, and of those, only about three are venomous and poisonous spiders and can put your life at risk, according to research published in American Family Physician. And if you’re wondering how long spider bites take to heal? While certainly itchy and annoying, most bites heal up within a week (other than brown recluse and hobo spider bites, which can unfortunately take weeks or much longer to heal, depending on whether you develop an infection).
But if you don’t happen to be a spider expert, how do you know if your spider bite is cause for serious concern—or how to make the itching and burning stop? The Instagram photos below (all reviewed by experts) will give you an idea of what different types of spider bites look like—and what you should do if you spot one on your bod.
A post shared by Arturo (@warmloaf) on Jan 6, 2018 at 2:15pm PST
Sometimes, spiders leave behind two distinct puncture holes right next to each other—but unless you actually see the spider do the dirty deed, it’s hard to know if it was caused by an arachnid or some other biting bug.
In fact, the vast majority of «spider bites» are actually bites from other insects like fleas, ticks, and mosquitoes; are a rash from an allergic reaction; or are skin abscesses from an infection, says Justin Arnold, D.O., assistant professor of emergency medicine at the University of Alabama at Birmingham, and the associate medical director of the Alabama Regional Poison Control Center at Children’s of Alabama.
The symptoms are often similar, too—pain, swelling, itching, and redness—so it’s an easy mistake to make. In fact, even spider experts and medical professionals have a hard time differentiating bug bites from spider bites just from how they look, he adds.
«Many people don’t recall an injury or specific bite and hold a common belief that a spider must have bitten them without them knowing,» he says. «In a majority of the cases that we see, a spider was never seen by patient and is not responsible for their infection.»
A post shared by @ yuckygross on Dec 19, 2016 at 8:11am PST
While poisonous bites are rare, any bite—spider or otherwise—can turn serious if it becomes infected, says Arnold. There are three main complications that can arise from bites: cellulitis, blisters, and swelling, says Arnold.
When a spider bite turns into cellulitis—a common (although painful) skin infection—a rash begins to spread around the wound, and the skin becomes painful and hot to the touch.
Another common reaction to many spider bites is to get «weeping» blisters at the site (they look puffy and fluid-filled). Small blisters on their own, with no other symptoms, don’t necessarily need special care. But if a blister opens, it becomes at risk for infection, says Arnold, so don’t try to pop them! If you think you may have an infection at the bite site, whether from cellulitis or open blisters, it’s best to have your doctor take a look.
Swelling is another very common symptom of insect or spider bites. Even though the swelling can get quite pronounced it’s not necessarily a problem, as long as it goes down within a few days. But if the swelling doesn’t go down, gets significantly worse, or is accompanied by other symptoms, it’s time to get medical attention, says Arnold.
A post shared by Helen Harding (@hchharding) on Jan 27, 2018 at 4:21pm PST
The two most common spider bites are from house spiders, specifically the jumping spider and the wolf spider. While it can be scary to be bitten by any spider, these bites normally aren’t any more painful than a bee sting and shouldn’t cause problems beyond some redness, swelling, and itching, Arnold says.
Treat these at home by washing the site with soap and water, using cold compresses, and taking an ibuprofen to reduce pain and swelling, he adds.
A post shared by Caitlin Miller Calder (@y2caitlin) on Apr 3, 2014 at 8:16am PDT
Of all of the spiders, black widows pose the greatest health threat to Americans, according to Rick Vetter, Ph.D., a spider expert in the department of entomology at the University of California, Riverside. Their bite is extremely painful and, while an antivenin (a.k.a. anti-venom) exists now, before it was discovered, about 5 percent of bitten people died.
Think you can ID a black widow bite on sight? Not so fast: The actual bite looks a lot like any other spider bite. However, they do tend to become more swollen and red than your general household spider bite, he says.
Black widow spiders are tough to identify, as well. Only female black widows have the characteristic red hourglass-shaped markings on their backs. Male and immature black widows have tan and white stripes, Vetter says.
Because these types of bites are so serious, if you strongly suspect you were bitten by a black widow or you develop muscle cramping, abdominal and chest pain, high blood pressure, a racing heart, and/or vomiting within two hours of a bite, go to the ER immediately, Arnold says.
A post shared by Ashley Parsons (@ashley_parsons) on Jul 13, 2015 at 10:00am PDT
The brown recluse (also known as the fiddleback spider or violin spider) is one of the most venomous spiders in America, but they are limited to very specific geographic regions—if you don’t live in one of these places, it’s highly unlikely you need to worry about this type of bite, Vetter says. (Check out this map to see if you’re in the danger zone.)
And despite what you may have heard, even where brown recluses are present, they rarely bite, he adds. To identify a brown recluse, look for six eyes arranged in pairs. (Although getting close enough to see the eye pattern on a spider sounds, frankly, terrifying.)
Brown recluse bites do happen though, and when they do, they are often described by «sharp burning pain,» Arnold explains. Within several hours, the bite area becomes discolored and forms an ulcer that can takes several weeks to heal. In addition to the wound, individuals can also develop fevers, muscle aches, and in rare cases, severe anemia as a result of the venom.
Start by treating any bite at home with cold compresses and an antibiotic cream, but if you start to show severe symptoms, including a lot of swelling, increased pain, fever, spreading rash or other sign of infection, get medical attention immediately, he adds. There isn’t an antivenin, but they can treat the symptoms and manage the infection.
A post shared by Evan (@eplevinski) on Sep 13, 2013 at 8:52am PDT
The hobo spider is actually a pretty common venomous house spider in the U.S., but despite some scary media reports, they’re not aggressive and will only bite if provoked, according to the U.S. Forest Service. In addition, about half of hobo spider bites are «dry,» meaning they contain no venom, the service adds.
If you do receive a venomous bite, within a few hours it will become red and hard, similar to a mosquito bite, and within a day or two will develop blisters. After the blisters open, a scab typically forms along with a rash that often looks like a target or bull’s eye.
Because these wounds can become necrotic (as in, infected to the point they start killing surrounding tissue) and can last for years in some cases, you should see a doctor immediately, Arnold says. There isn’t an antivenin but they can treat the symptoms and manage any infection with antibiotics.
Hobo spiders can be hard to identify, according to the Forest Service. They are large and often have chevron-type markings on their backs, but these won’t be visible on darker-skinned adult spiders, which is why it’s important to get any bite checked out if it starts to show signs of infection or you see a target forming on your skin, Arnold says.
A post shared by Chrissy (@porcelainbones84) on Mar 24, 2013 at 11:47am PDT
Tarantulas may look big and scary, but most of the North American varieties are pretty chill. And even while the bite itself can be painful, the venom is fairly benign and likely won’t cause long-term issues, Arnold says. Like most spider bites, tarantula bites can cause some swelling, itching, and irritation.
However, he adds, tarantulas also have the ability to flick hairs off of their body and into your skin, which can be very irritating and painful. And some people are allergic to tarantula venom, which can make the bite even more inflamed, according to the National Institutes of Medicine.
Most of the time, it’s fine to try treating these at home by washing the site, applying ice, and taking ibuprofen, he says. But if you find yourself having a more extreme reaction, including symptoms like rapid heart rate or difficulty breathing, get to the emergency room.