Though many people have a fear of spiders, most species rarely bite and are harmless. Only a few species across the world have fangs long enough to pierce human skin and deliver venom. In North America, the black widow and brown recluse spiders are particularly dangerous, and their bites often require medical attention.
Learning the most common spider bite symptoms and those of the more threatening species can help ease your fears and avoid potentially life-threatening complications.
Spider bites tend to look like any other bug bite: red, inflamed bumps. Depending on the species, the bite may not even be noticeable. More dangerous bites may have a pale center that slowly changes color. Some might be surrounded by bruising and form a blister.
Most spider bites are barely noticeable, though they may come with a slight itching sensation. The initial bite usually involves little or no immediate pain, though some species’ bites feel like pinpricks.
Bites from the more dangerous species can be more painful as time progresses, usually within the first hour.
Spiders can thrive across a wide range of habitats. Widow and recluse spiders, which pose the largest threat to the average person, like dry, warm climates with low light conditions. Sheds, garages, and attics are often the perfect homes for spiders.
Unused machinery or equipment, spaces between furniture, bedding, and wood piles are all also potential spider nesting grounds. Some species hide underground, between rocks, and under piles of leaves.
Black widow spiders are easy to recognize thanks to their round, black bodies and red hourglass shape on their abdomens. Widow bites cause immediate, sharp pain, like a poke with a needle. The bite area then radiates a dull or numbing pain.
Due to the nerve-toxic venom, widow bites cause cramping and muscle stiffness in the back, chest, shoulders, and—most commonly—the abdomen. Some people experience nausea, vomiting, itching, breathing issues, headaches, and increased saliva production.
Brown recluse spiders, also called fiddleback or violin spiders, are nonaggressive spiders with brown violin-shaped marks on their bodies. In many cases, brown recluse bites are mild and largely asymptomatic. However, the tissue-destroying venom of a brown recluse can lead to severe necrosis.
The bite tends to resemble a blister with a surrounding bruise or reddish color. The blister can change color to blue or purple and then rupture, resulting in an open wound. Itchiness may affect the bite area or all over the body. Pain is often minimal immediately after being bitten but worsens significantly as time goes on.
Wolf spiders are a widespread species of spider that live in solitude and do not spin webs. Historically, some researchers believed that wolf spider bites were necrotic, similar to those of a brown recluse. However, careful study has not supported this.
Instead, experts warn that wolf spider venom can cause minor issues, such as swelling, mild pain, and itching.
Depending on the severity, even bites from the more dangerous spider species are treatable at home. However, because of the potential for complications, seek medical attention for any bite that causes symptoms beyond a red bump.
If the person's skin begins to decay, regardless of the source, seek medical care immediately. Severe symptoms, such as fatigue, difficulty breathing, seizures, or muscle pain and weakness often require more intensive care and hospitalization.
First aid for a spider bite requires cleaning the wound with soap and water. Apply a cold cloth or compress to the area to reduce swelling and elevate the bite location if possible.
Doctors may use muscle relaxants to combat widow spider bite symptoms or, in serious cases, administer an antivenom. Recluse bites often heal without issue as long as they receive daily cleanings with a povidone-iodine solution and saline soaking. In extreme cases, surgery may be necessary.
Mild spider bites are easily treatable at home. Always start with the first aid steps for spider bites. Some people find that aloe vera gel can provide some relief for itchiness and swelling. A small amount of evidence points to chamomile as having anti-inflammatory properties that can help with irritation.
Do not attempt to treat severe spider bite symptoms at home.
Most spider bites heal well with no complications. However, certain factors can dramatically increase the risk. Recluse bites sometimes take weeks to months to heal and result in large scars. Spider bites are also far more lethal for people under the age of 16 or over the age of 60, as well as those with heart problems, blood pressure issues, and allergies. Rarely, widow bites can lead to organ failure.
This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.