Spider Bites
Almost all spiders are poisonous. However, the fangs of most
species are too short or too fragile to penetrate human skin. Although at least
60 species in the United States have been implicated in biting people, serious
injury occurs mainly from only two types of spiders:
The widow (black widow) spider
The brown (brown recluse, fiddleback, or violin) spider
Black Widow Spider
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Brown spiders are present in the Midwest and South Central
United States, not in the coastal and Canadian border states, except when
imported on clothing or luggage. Widow spiders are present throughout the
United States. Although some people consider tarantulas dangerous, their bites
do not seriously harm people. Spider bites cause fewer than three deaths a year
in the United States, usually in children.
Bites and Stings Myths
Bites and Stings MythsPODCAST
Serious injuries from spider bites can include severe wounds
caused by the tissue-destroying venom of brown spiders and bodywide poisoning
caused by the nerve-toxic venom of widow spiders.
Wounds suspected of being caused by the brown spider are
often caused by other problems, some potentially more serious.
Brown spider bites are treated by caring for the wound.
Widow spider bites are treated by relieving symptoms and
sometimes giving antivenom.
Brown Recluse Spider
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Symptoms of Spider Bites
The bite of a widow spider usually causes a sharp pain,
somewhat like a pinprick, followed by a dull, sometimes numbing, pain in the
area around the bite. Cramping pain and muscle stiffness, which may be severe,
develop in the abdomen or the shoulders, back, and chest. Other symptoms may
include nausea, vomiting, sweating, restlessness, anxiety, headache, drooping
and swelling of the eyelids, rash and itching, severe breathing problems,
increased saliva production, and weakness.
Did You Know...
Although tarantulas are large and may appear frightening,
their bites do not seriously harm people.
Brown Recluse Spider Bite
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The bite of a brown spider may cause little or no immediate
pain, but some pain develops in the area around the bite within about an hour.
Pain may be severe and may affect the entire injured area, which may become red
and bruised and may itch. The rest of the body may itch as well. A blister
forms, surrounded by a bruised area or by a more distinct red area that
resembles a bull’s-eye. Then the blister enlarges, fills with blood, and
ruptures, forming an open sore (ulcer) followed by a thick black scar (eschar)
that may leave a large crater-like scar. Uncommonly, nausea and vomiting,
aches, fatigue, chills, sweating, blood disorders, and kidney failure develop.
Diagnosis of Spider Bites
A doctor's evaluation
If possible, identification of the spider
There is no way to identify a particular spider on the basis
of its bite mark. Therefore, a specific diagnosis can be made only if the
spider can be identified. Widow spiders are recognized by a red or orange
hourglass-shaped marking on the abdomen. Brown spiders have a violin-shaped
marking on their back. However, these identifying marks can be difficult to
discern, and the spider is rarely retrieved intact, so the diagnosis is usually
uncertain and based on symptoms. Many people mistake skin infections, some
potentially serious (such as methicillin-resistant Staphylococcus aureus [MRSA]
infections), or other disorders for spider bites.
Treatment of Spider Bites
Cleaning the wound and applying ice
For widow spider bites, drugs to relieve pain and muscle
spasms and often antivenom
For brown spider bites, wound care and sometimes surgical
wound repair
First-aid measures for a spider bite include cleaning the
wound, applying ice (for example, an ice cube or crushed ice in a plastic bag
and wrapped in a thin cloth because ice should not be applied directly on the
skin) to the bite to reduce pain, and, if the bite is on an extremity,
elevating the wound site.
For a widow spider bite, muscle pain and spasms can be
relieved with benzodiazepines (which sedate and may help relax muscles) and
opioids (analgesics). Antivenom is given for severe and sometimes for moderate
poisonings (those that cause muscle cramping or other bodywide symptoms).
Hospitalization is usually required for people younger than 16 or older than 60
and for people with high blood pressure, heart disease, or severe symptoms.
Did You Know...
Many people falsely assume that they were bitten by a spider
when they really have another disorder, such as a skin infection.
Most brown spider bites heal without complications. Sores
should be cleaned daily with a povidone-iodine solution and soaked 3 times a
day in sterile salt water (saline). Moderately to severely damaged wounds may
require surgical procedures.