How to Identify and Treat Black Widow Spider Bites

Last Updated: July 4, 2022 References

Most spider bites are harmless. It is sometimes difficult to tell a spider bite from another insect sting or bite, or even just a mild skin infection. Always seek medical attention if you are not sure of what caused a serious bite or sting, especially if you begin to develop symptoms. The two most common poisonous spiders found in the United States are the black widow and the brown recluse. If you have confirmation that the bite was from a black widow spider, then be sure to seek immediate medical care.

Part 1

Part 1 of 3:

Identifying a Bite from a Black Widow Spider

1
Recognize a bite from a black widow spider. Black widow spiders have fangs. When bitten, two small puncture wounds are usually visible.^{[1]
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- As the venom from the bite spreads, the area develops a target-like appearance. The fang marks are in the center, surrounded by an area of reddened skin, then another circle of red just a little further beyond the center.
- The fang marks are visible immediately. Redness and swelling of the area where the bite occurred develops rapidly, usually within an hour.
- Pain typically starts within the hour and can quickly spread from the site to systemic areas such as the abdomen, chest area, or back.
- This is not always the case, but this is the classic description for the pattern that develops from a black widow spider bite.
2
Capture the spider if possible. The treating physician will want to know what caused the bite/sting/injury. Safety is always the priority. If you can safely capture the spider, place it a container that does not present a risk of injury to anyone else. A small glass jar or plastic container with a lid, placed inside another container with a secured lid and handle, such as a small cooler, can help to make it easy to transport the spider.^{[2]
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- Clearly no one needs to be put at risk of being bitten. If it can be done safely, capture the spider and safely take it with you to the medical facility.^{[3]
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- Presenting the spider that did the biting can help in initiating the most effective treatment as quickly as possible. Carrying around a black widow spider might not be the best plan, so at least take very clear pictures of whatever bit you, if you can do so safely.
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3
Recognize the symptoms. Most people that are bitten by a spider, including a venomous one like a black widow, do not have any serious medical problems as a result.^{[4]
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- Symptoms that can result from a black widow bite include severe and intense pain, stiffness, muscle cramps, abdominal cramps, back pain, excessive sweating, and hypertension.
- Both topical and systemic reactions to the venom from a black widow spider can develop and spread quickly. Seek treatment as soon as possible once you confirm, or are fairly sure, you were bitten by a black widow spider.
- Topical reactions include itching or rash at the site, sweating of the extremity where you were bitten, pain radiating from the site, and discolored areas of the skin that form blisters.
- Systemic reactions include severe and intense muscle pain, pain radiating to the back and chest area, sweating, difficulty breathing, headache, nausea and vomiting, fever and chills, elevated blood pressure, and anxiety, restlessness, and delirium.

Part 2

Part 2 of 3:

Treating the Black Widow Spider Bite

1
Initiate treatment. The first step in treatment is to stay calm and safely identify the spider.^{[5]
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- Wash the area with mild soap and water and use ice applications or a cold cloth to help prevent swelling.
- Do not apply ice directly to the skin. Use a towel or soft and clean cloth between the skin and the ice-filled baggie or cold pack.
- Elevate the area that was bitten if possible and practical.
- Take an over-the-counter product to help with pain and/or inflammation such as acetaminophen, ibuprofen, naproxen, or aspirin. Be sure to follow the directions on the label.
2
Seek medical care. According to reports from poison control centers in the United States, more than 2500 incidents of black widow spider bites are reported each year in the United States. Go to an urgent care clinic or hospital emergency room.^{[6]
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- You may want to call your regular doctor and inform him or her of the situation. Your doctor may want you to come straight to the office or have a preference as to the medical facility you go to. Wherever you end up going, inform them that you are on your way and that you were bitten by a black widow spider — this will give the staff ample time to prepare.
- Do not attempt to drive yourself to the hospital. The venom from the bite can alter your responses abruptly. You may feel lucid when you start driving, but your condition can change quickly.
- Most people do not experience severe reactions from a black widow spider bite. In fact, some people have no problems at all and do not need medical care.
- Due to the possibility of severe pain, discomfort, and systemic changes, talk with your doctor as soon as possible or go to an emergency room or urgent care clinic to be sure you can receive prompt treatment should you develop any adverse effects or complications.
- Inform the doctor at the treatment facility of all medications or treatment steps taken upon arrival.
- Fortunately, only three cases of death have been recorded over many years.
- Some reports of serious complications and death have been linked to black widow bites in people that were already severely medically compromised.
3
Use the antivenom, Antivenin Latrodectus Mactans. The antivenom has been available since the 1920s. At least one case report of a severe hypersensitivity reaction has limited the use of the antivenom in the United States.^{[7]
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- Complications from the bite are possible. A medical facility can monitor your vital signs and changes in your condition to determine if treatment is warranted.
- An article published in 2011 reviewed four cases of black widow spider bites. Three of the people bitten were treated with the antivenom and one was not due to concerns over hypersensitivity.
- The three people treated with the antivenom experienced relief from the severe pain caused by the bites in a short period of time, usually with 30 minutes of receiving the injection. All three people were observed for a few hours in the emergency treatment facility then discharged to home without further complications.
- The person that did not receive the antivenom was treated with strong pain and anti-inflammatory medications in the emergency department, then required admission to the hospital.
- The person received treatment in the hospital for two days, then began to feel better by the third day. He was discharged to home on the third day without further complications.

Part 3

Part 3 of 3:

Recognizing a Black Widow Spider

1
Identify the black widow spider without disturbing it. The unique marking of a female black widow spider is the bright red hourglass shape on the underneath part of its abdomen.^{[8]
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- The female spider has a black and shiny body with a large and round abdomen. The body is about 1 and ½ inches in length, and the entire spider, legs and all, is more than 1 inch across.
- They have fangs that are a little shorter than those of other spiders, yet still long enough to penetrate human skin.
- Black widow spiders are reported to be commonly found in the southern and western regions of the United States. Other sources and statistics report frequent sightings as far west as California, all along the eastern seaboard, south to Florida, and north as far as Okanagan in BC and central Alberta in Canada.
2
Spot possible places where they like to live. Black widows like to live outside where there are plenty of flies to feed on; however, they can be found inside structures and shelters.^{[9]
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- They prefer undisturbed places such as woodpiles, under simulated rock well covers, the eaves of a house, around fences, and other areas where debris piles up.
- Watch for black widows in dark, moist, and undisturbed places like meter boxes, under porches, porch furniture, and inside and around barns and sheds.
3
Try not to disturb the web. Black widow spiders like to make their webs between objects that are solid and stationary. Some spiders prefer to make their webs in locations that are more flexible, like between shrubbery and tree branches.^{[10]
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Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services
Go to source}
- The black widow's webs are purposefully made in an irregular shape, not like the typical and sometimes practically perfect webs made by other spiders. The fibers of the web are stronger than those found in most spider webs.
- They don't prey on human skin. Most bites occur when their webs are disturbed.
- They are not aggressive but will bite when they feel trapped or are touched.
4
Differentiate the males from the females. The females have the classic markings and the more potent venom. If you are bitten by a female black widow, then you need prompt medical attention.^{[11]
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- The body of a female is usually larger in size than a male black widow spider, however the legs of a male are often longer. This can make the overall size of the male appear larger.
- Males can be black but are usually brown in color, and the markings can be anywhere on the abdomen. The red is typical yet some males have markings that are white or brownish.
- The female has the traditional hourglass red shape on the abdomen, but this can appear more orange than red in some females.
- Females have fangs large enough to penetrate human skin and deliver enough venom to create a systemic reaction.
- Bites from male black widow spiders are not considered to be capable of delivering venom.
- The black widow spider was named for the tendency of the female to eat the male after mating. This is not always the case, but it is a real possibility.