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Are Brown Recluse Bites Dangerous?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

For the most part, bites from brown recluse spiders are not dangerous. In rare cases, a bite may cause tissue necrosis and a large ulceration which can take a long time to heal, and may expose the patient to the risk of infection. Even more rarely, brown recluse bites can lead to death, with deaths being isolated to very young children, older adults, and people who are in poor health.

One of the biggest problems with brown recluse bites is that they are overdiagnosed. These spiders are very shy, and typically will not bite unless antagonized or threatened. People often do not notice the spider when it bites, and a doctor may be inclined to diagnose a lesion which looks like a brown recluse bite as a spider bite, even if it later turns out to be something else. For example, many painful ulcerations of the skin which are thought to be brown recluse bites are actually examples of severe staphylococcus infection.

Many spider bites -- from such spiders as the brown recluse -- go unnoticed or cause only minor irritation -- unless a person is allergic to spider venom or the venom is poisonous.
Many spider bites -- from such spiders as the brown recluse -- go unnoticed or cause only minor irritation -- unless a person is allergic to spider venom or the venom is poisonous.

If a spider does bite, the patient can experience a sharp pain at the site of the bite. A white blister may appear, fading to a red dot which disappears in a few days or weeks. The patient may feel mildly ill with nausea and fever until the body can process the spider venom. Often, the only treatment required is ice on the wound and rest until the patient feels better.

A patient may feel mild nausea and fever after a spider bite while the body processes the venom.
A patient may feel mild nausea and fever after a spider bite while the body processes the venom.

If the spider injects a lot of venom and the patient is especially sensitive, brown recluse bites become necrotic, with tissue around the bite dying and sloughing off. This leads to an exposed ulcer which can be painful and very unpleasant to look at. As long as the ulcer is kept clean and dry, it should heal within six to eight weeks. Some ulcerations may require more extensive medical treatment, such as a skin graft or medications to control infections. In vulnerable patients, venom sensitivity can lead to death as a result of a brown recluse bite.

Brown recluse bites are more serious for older individuals.
Brown recluse bites are more serious for older individuals.

The important thing to be aware of is that brown recluse bites are incredibly rare. This spider is found mostly in the American South, and when people do encounter brown recluses, the spiders are usually quite reluctant to bite. People who develop skin ulcerations or lesions which they suspect may be the result of an insect or spider bite can seek medical treatment, and should definitely seek treatment if there are signs of infection or other complications, but they should encourage their doctors to rule out other causes for the lesion, rather than assuming that it is a bite. Failure to diagnose the correct cause can lead to a delay in getting the right kind of treatment.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a TheHealthBoard researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

6pack

I live in Los Angeles. A neighbor just told me that she is suffering from a brown recluse infestation in her apartment. She got a spider bite while she slept which she thought was innocuous until it enlarged and hurt. She visited the hospital and the physician diagnosed it as a brown recluse spider bite and gave her antibiotics.

In trying to get rid of the spiders in the apartment, she's asked pest control to come and spray but she was told that the spray is not very effective as the spray can't get into the crevices that the spiders typically hide in.

As a result, and upon the suggestion of others, she bought some geckos to roam the apartment to naturally take care of the brown recluse infestation problem. (I'd rather see a cute gecko run across my floor than spiders that can bite too.)

I saw my first brown recluse in my apartment today. I have heard that more recently there has been an increase in brown recluses in California -- perhaps caused by someone bringing the spider from a location where they used to be more commonly restricted to.

Thanks for the article. I appreciate the calm it provides to a subject that at first had me a bit rattled.

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    • Many spider bites -- from such spiders as the brown recluse -- go unnoticed or cause only minor irritation -- unless a person is allergic to spider venom or the venom is poisonous.
      By: schankz
      Many spider bites -- from such spiders as the brown recluse -- go unnoticed or cause only minor irritation -- unless a person is allergic to spider venom or the venom is poisonous.
    • A patient may feel mild nausea and fever after a spider bite while the body processes the venom.
      By: danilkorolev
      A patient may feel mild nausea and fever after a spider bite while the body processes the venom.
    • Brown recluse bites are more serious for older individuals.
      By: Rido
      Brown recluse bites are more serious for older individuals.
    • A sharp pain may occur at the site of a spider bite.
      By: ronstik
      A sharp pain may occur at the site of a spider bite.
    • One of the biggest problems with brown recluse bites is that they are overdiagnosed.
      By: Jürgen Fälchle
      One of the biggest problems with brown recluse bites is that they are overdiagnosed.
    • Some brown recluse bites may lead to tissue necrosis.
      By: Remus Moise
      Some brown recluse bites may lead to tissue necrosis.
    • Brown recluse bites may cause a blister or red spot or other rash.
      By: Arve Bettum
      Brown recluse bites may cause a blister or red spot or other rash.
    • Nausea may occur as a result of a spider bite.
      By: Alliance
      Nausea may occur as a result of a spider bite.