February 23, 2022

What To Do for a Spider Bite

Here’s when to worry about these creepy crawlers

spider on skin

If you’re afraid of spiders, you’re not alone. Many people fear these eight-legged insects. In more serious cases, this fear can even have an impact on your day-to-day life. In fact, there’s a specific word to describe a very intense fear of spiders or other related creepy crawlers: arachnophobia.


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In addition to shying away from spiders, spider bites might fill you with fear, too. While it’s true that some spiders have venom that’s harmful to humans, most don’t — and you can treat any bite effectively by following some very simple steps.

Emergency physician Christopher Bazzoli, MD, FAWM, DiMM, breaks down what to do for a spider bite, including how to treat a spider bite at home.

How to tell if you’ve been bitten by a spider

Spider bites might not look or feel like you’d expect them to. For example, Dr. Bazzoli notes that a spider bite won’t likely consist of two puncture wounds — a common depiction of a spider bite — because the insects are so small. “Spider bites are going to appear like single bites,” he says. “If you have lots of bites in an area, you can also be assured that it is not a spider.”

It’s also a misconception that all spiders have gigantic fangs. “Many skin lesions or skin abnormalities get blamed on spiders,” Dr. Bazzoli says. “In reality, the vast majority of spiders don’t have big enough fangs to actually break human skin. And very few spiders that do have the size and strength to break the skin have a venom that can actually harm humans.”

In fact, the sex of the spider also dictates the size and scope of bites. In North America, female brown recluse and black widow spiders are larger and often have a more serious impact. “They have larger fangs, can bite deeper and release more venom,” says Dr. Bazzoli. “Male spiders typically can’t penetrate the skin in most places on the body, only thinner skinned areas.”

Because of these small fangs and lack of effective venom, you may not feel a spider bite at all — even from a potentially harmful type of spider.

But Dr. Bazzoli says you’ll “definitely feel” bites from larger spiders like black widows or tarantulas. “Typically, it feels like a sting or a bite from a biting fly,” he explains. “A sharp pain initially. What happens next depends on the type of spider and their venom.”

Dr. Bazzoli notes this phenomenon also holds true for most spider bites. In general, spider bites initially often look like the ones you’d get from another insect. But in the hours or days after a bite, you may be able to tell whether you were bitten by a spider — or a mosquito, flea, tick or hornet — by symptoms that emerge.

Dangerous symptoms of a spider bite

In North America, the two spiders with venom that are poisonous to humans include the brown recluse and black widow. Systemic signs of illness from one of these bites can include:

  • Muscle cramping.
  • Abdominal pain.
  • Nausea and vomiting.
  • Feeling very fatigued — children especially.
  • Body aches.
  • Change in urine color, especially to a “very dark, cola-colored urine.”

Within the first day of a spider bite, Dr. Bazzoli says you’re going to know if it’s going to be a big problem — or a potential problem. “If the bite is from a dangerous spider, those kinds of symptoms that affect your entire body are typically going to come on anywhere from half an hour to several hours, eight to 10 hours, after the bite,” he notes. “And those would definitely be reasons to seek medical care in the emergency department.”

What to do for a spider bite

First and foremost, if you feel a sting, try looking for what bit you. “Ask yourself, ‘OK, do I actually see a spider? Or do I see some other insect?’” Dr. Bazzoli says.

“If you feel a sting under your clothes, try and shake out your pant leg and see what insect or critter drops out. This can help you determine whether you have a spider bite and, if so, what kind of spider bite it was — or if this was a sting from something else.”

If you’re unclear on your bite’s origins, err on the safe side and follow the same directions doctors recommend you use to treat a regular bite or another skin wound.

“Frequently, what gets blamed as a spider bite is a secondary infection to a small nick in the skin or a bite from some other insect,” says Dr. Bazzoli. “Anytime your skin is bitten or scratched or scraped, it’s really important to wash and keep things clean because that open skin area is the perfect place for bacteria to sneak in and set up an abscess or infection.”

Here’s how to treat a spider bite:

1. Wash the bite with warm, soapy water

Take a gentle cloth and wash (and then rinse) the bite. Cleaning the spot is really important, says Dr. Bazzoli. “The best thing you can do to reduce the chances of it getting infected is to clean things out really well. We have a saying — the solution to pollution is dilution.”

2. Apply ice to the bite


Fill a baggie with ice (or use an ice pack) and apply it to the bite — 15 minutes on, and then 15 minutes off. Repeat as needed.

3. Take over-the-counter meds

Soon after you’ve been bitten — or notice a bite — take a regular dose of over-the-counter anti-inflammatory pain medicine. For adults, Dr. Bazzoli notes that means 500 to 1,000 milligrams of acetaminophen (Tylenol®) or 400 to 600 milligrams of ibuprofen (Advil® or Motrin®).

“Those medicines help reduce the inflammatory response,” he explains. “Taking those medicines earlier will help reduce swelling and the redness. In doing so, that will also reduce the amount of pain that you have.”

4. Consider a tetanus shot or booster
If a bite is serious or resembles a puncture wound, you might have to talk to your doctor about getting a tetanus shot or booster. “You want to stay up to date with your tetanus shots and get a tetanus booster every 10 years,” Dr. Bazzoli advises.

Are there home remedies for spider bites?

Dr. Bazzoli says applying aloe or peppermint oil to a bite can have some positive effects on a spider bite. Both offer a cooling sensation, which can feel good on your skin. And while neither helps with wound care, aloe has been shown to promote tissue healing.

But other home remedies commonly associated with treating spider bites — baking soda, lemon juice, salt, charcoal — aren’t effective or recommended.

“The reasoning for using a lot of these things is that people think you can use them to draw out a toxin, or draw out or neutralize the venom,” says Dr. Bazzoli. “But there’s never been any proven evidence that we can suck out or neutralize venom once it’s injected into tissue. The venom gets picked up by tiny capillary veins below the surface of the skin so quickly that it’s gone before you can draw it back out.”

You also shouldn’t cut into the bite to try removing venom or make your skin bleed. “We definitely would recommend against that,” Dr. Bazzoli says. “Again, the venom is going to spread to the tissue very quickly. You’re not going to be able to somehow push it back out. All you’re going to do is open up a way for bacteria to get in to the tissue layers below the skin and potentially cause an infection.”

How common are spider bites?

First off, you can sleep easier at night: Spider bites are actually rather rare. “Our best estimates are that somewhere around 50,000 to 100,000 people are bitten by all insects every year — of which we estimate no more than about 25,000 people are bitten by spiders annually,” says Dr. Bazzoli. “With a little over 330 million people in the United States, that works out to somewhere around 1 in 12,000 to 1 in 15,000 people per year are bitten by spiders.”

Plus, although spiders often have a reputation for being mean or scary, Dr. Bazzoli says that’s a total misconception. “They’re fairly shy creatures. They’re not naturally aggressive. They’re not a wolf of the insect world. They’re not a predator going out and seeking to take down a prey, especially one as big as us.”

He adds that one exception might be tarantulas (they can lash out in certain situations, such as if they sense sudden movement around their webs) or female black widow spiders who’ve laid eggs. “But the vast, vast majority of spiders want nothing to do with us,” he assures.

Dangerous bites to look out for

As noted, both the brown recluse and black widow spiders are “very shy,” says Dr. Bazzoli. “They typically like to hang in cool, dry, darker places.” He notes this includes garages, attics and storage facilities — “the back corners where you put things away and haven’t touched them in a year. That’s where they like to make their nest because they really don’t like company.”

If you’re bitten by a black widow or brown recluse spider, don’t panic. “The vast majority of people do not have a significant reaction,” Dr. Bazzoli says. “Most of us, even when bitten by a black widow or brown recluse, don’t have any issues and don’t go to the hospital.” However, there are warning signs to watch out for after a bite.

Brown recluse spider bites

The venom released from a brown recluse bite is toxic to tissue cells, but it’s a local venom. In other words, the venom doesn’t travel throughout your body, but instead, stays put and affects the skin tissue where the bite occurred.

Dr. Bazzoli says between one to three days after a brown recluse bite, you’ll often see what looks like a bruise and redness near the bite area. “You’ll see that black and blue color, mixed with red. Many people will say it’s a red, white and blue-type of bite.”

In the coming weeks, the center area of the bite typically will scab over. That’s something to keep an eye on, Dr. Bazzoli cautions. “When those areas of tissue are killed, in their place is a shallow ulcer, or an open wound,” he notes. “In about 10% of cases of more severe brown recluse bites, you’ll need a plastic or general surgeon to basically clean out that ulcer. You may even need a small skin graft to reduce scarring.”

Luckily, brown recluse spiders aren’t looking to bite you.“They’re total chickens,” says Dr. Bazzoli. “Most of the time when you get a brown recluse bite, it’s because you’ve managed to get one pinned in your clothing or started to crush it with your hands. Maybe you’re putting on old clothing or taking old clothing out of a box. If you stick your hand into their web, they’re probably going to run away, or they might run up your hand and into your shirt.”


Black widow spider bites

Black widow spiders also hang out away from people. But at different times of the year, you need to be cautious. “Especially during breeding season, when they’re laying eggs, female black widow spiders can be a little bit more defensive,” says Dr. Bazzoli. “We often see black widow bites on the hands and the ankles — the places where people are reaching into an area.”

You’ll typically have redness around the area of a black widow bite. In the time after the bite, though — which can range from half an hour to eight or 10 hours later — you may start noticing other symptoms. These include pain, a cramping-like sensation, spasms and sometimes tingling in the hand or foot with the bite.

“This happens because the black widow venom is what we call a neurotoxin,” Dr. Bazzoli explains. “Instead of staying in the tissue where the bite happened, like the brown recluse, the venom spreads throughout your circulatory system. It spreads out through very tiny blood vessels and it starts to affect your neurotransmitters.”

Neurotransmitters are chemicals used by nerve cells that direct your body’s functioning. When these are affected by a toxin, this can cause body-wide symptoms such as headaches, abdominal pain, muscle cramping, nausea and vomiting.

“You can sometimes feel very flushed and sweaty — almost as if you’ve received a shot of adrenaline,” says Dr. Bazzoli. “Your heart rate and blood pressure can be up.” Children especially need to be careful if bitten by a black widow because the venom can affect them more severely.

Tarantula spider bites

Contrary to what you might think, tarantulas in North America aren’t dangerous to humans. “The venom of tarantulas in North America is quite toxic to dogs,” says Dr. Bazzoli. “However, tarantulas in North America do not have a venom that is toxic to humans. You can have a painful bite, but it would be no different than being bitten by something like a bee or biting fly.”

Tarantulas do have a rather unique defense mechanism against predators, though. These spiders can take their leg and actually throw hairs off of their belly. These hairs contain tiny barbs that can stick in your skin.

“In North America, our tarantulas also have the least dangerous kind of barbs,” Dr. Bazzoli says. “They stick in the skin but don’t go in very far and aren’t very big. However, they can be irritating and cause itching and some redness wherever the hairs have landed.”

To remove the hairs, stick tape over the area — duct tape, masking tape or even just Scotch® tape works — and then remove it quickly.

Just make sure you don’t get one of these tarantula barbs in your eye.

“If you’ve been up close with a tarantula who gets spooked and is defending itself, you can catch those barbs in the eye,” says Dr. Bazzoli. “If you feel irritation and pain in the eye, you should definitely go to the doctor, preferably an eye specialist such as an optometrist or an ophthalmologist.”

Other bites

Like other insect bites, spider bites can also cause an allergic reaction affecting multiple parts of your body (what doctors call a systemic reaction). Signs of this type of widespread allergic reaction include:

  • Feeling short of breath.
  • Breaking out in hives.
  • Feeling itchy all over.
  • Vomiting or feeling nauseated.

“If you’re showing any of those signs, you should definitely be seen by a healthcare practitioner,” stresses Dr. Bazzoli. How quickly those symptoms come on depends on how fast you should seek help, he adds. “If the symptoms come on all of a sudden, and you can’t breathe, call 911. If you break out in hives and are itching, and they seem to be spreading, take some Benadryl® at home. You may be able to simply go to an urgent care later or call your doctor’s office for an appointment later that day to be evaluated.”

Spider bites can be anxiety-inducing and traumatic. However, staying vigilant and washing out the bite well can go a long way to keeping you healthy.

“Spider bites are like any other bites,” says Dr. Bazzoli. “Sometimes, you can be bitten and it hurts a little bit and you do fine. At other times, three or four days later, maybe the bite area starts to swell. And certainly, if you have a pocket of infection, or an abscess or blister forming, that would also be a reason to go to your doctor. They can make sure that you don’t need a course of antibiotics or a pocket of infection lanced open. But the vast, vast majority of problems can be prevented by washing the bite out very well.”

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