Spider bites are common, and most do not require any medical treatment. However, the bite of the black widow and brown recluse, two species found in the United States, can cause harmful symptoms.
Additionally, you may be allergic to a certain spider’s venom and experience serious side effects from the bite.
Other types of spider bites can be treated at home and symptoms should subside after 1 to 2 days.
Lingering or worsening symptoms may be a sign of infection and require the care of a doctor.
Generally, a spider bite will not require medical care. But there are a few reasons you may need to get immediate medical treatment for a spider bite.
Call 911 and go to the nearest emergency room if:
- you suspect or know a black widow or brown recluse spider bit you
- you have an allergic reaction to a spider’s venom (see below)
- your symptoms get worse over time
If you know you were bitten by a venomous spider
If you can capture the spider, bring it to the hospital in a container. This will help the doctor identify the type of spider and treat your bite.
If you know you are allergic to spider venom or have a serious reaction
You may experience an allergic reaction after a spider bite, regardless of the type of spider that bit you. Symptoms of an allergic or severe reaction to a bite include:
- trouble breathing
- loss of consciousness
- severe swelling or itchiness at the bite site or in your throat or eyes
- fast heart rate
These symptoms may be signs of anaphylaxis, where your entire body reacts to the allergen. This is a medical emergency and needs immediate treatment.
If your bite has gotten worse
Keep an eye on any area of skin where you suspect a spider bite. Symptoms that get worse over time may indicate that you were bitten by a venomous spider or that the bite is infected.
Worsening symptoms include:
- pain near the bite after 1 to 2 days
- enlarged wound site
- redness streaking from the bite
- muscle cramps
- flu-like symptoms
In many cases, you can treat a spider bite at home. You may experience mild symptoms for 1 to 2 days. Bites that itch or are infected may require more treatment and a consultation from a doctor.
Clean the bite area
Wash the bite area with soap and water. Keep the area clean while it heals to reduce the chance of infection.
Apply ice to the bite for 10 minutes at a time. Wrap the ice in a cloth to avoid too much cold exposure. Elevate the area while you ice it if the bite is on a leg or arm.
Medical treatment for a spider bite depends on your symptoms and the type of spider bite. Mild symptoms that linger could require over-the-counter medications. Symptoms that are moderate or severe may require prescription medication or supervised care.
Over-the-counter antibiotic ointments may help an infected bite. Follow the directions on the medication’s packaging and cover the bite with a bandage after using the ointment. Your doctor may prescribe a more powerful topical application, if needed.
You may need an over-the-counter or prescription antihistamine to relieve itching and swelling from the spider bite. Follow the directions on the packaging.
Pain relievers may be needed to calm pain from spider bites. Over-the-counter options include acetaminophen and ibuprofen.
A doctor may prescribe antibiotics if you have a brown recluse spider bite or if your spider bite becomes infected.
Benzodiazepines and opioids
Black widow bites may require more aggressive medication.
Intravenous administration of benzodiazepines or cyclobenzaprine may be used to treat the muscle cramps and pain caused by black widow venom, according to the journal U.S. Pharmacist. Opioids may also be used in the short term because long-term use can increase the risk of dependence.
If you have severe symptoms following a black widow bite, your doctor will administer an antivenin intravenously. There is no antivenin for brown recluse bites.
The most dangerous spiders in the United States are the black widow and brown recluse. Other spider bites could result in a reaction if you are allergic to their venom.
Black widows are black or brown with a red hourglass shape on the top of their body. They can also be black with red legs. You may see two puncture marks where the black widow bit you.
Black widow venom will affect your nerve tissue. The bites are immediately painful. You’ll also notice swelling right away. Your muscles will begin to cramp after an hour or more, including in your chest or abdomen. Other symptoms include:
- difficulty breathing
Black widows live in the Southern and Western states. You may find them in dark, secluded areas like wood piles, corners of a structure, and debris piles.
Brown recluse spiders are brown and have a marking on their head that looks like a violin.
Brown recluse spider venom can kill skin tissue and cause scarring. Initially, you may feel minimal pain from the bite, but it will become more painful. Blisters will develop a few hours after the bite. After a few days, the skin will curve downward and appear blue. You may also experience flu-like symptoms like fever or vomiting.
You will find brown recluse spiders in the Central and Southern United States. They live outdoors and indoors.
Some believe that hobo spider venom has similar skin-decaying effects to a brown recluse, but this is disputed. This is a large house spider with long legs that can run quickly.
Hobo spiders live in the Western United States.
This is a small indoor spider with a hairy body. It can jump and lives near windows. Bites are not harmful unless you are allergic to the venom.
Wolf spiders are brown like the recluse but do not have the ornamental violin shape on their heads. These spiders are not harmful to humans. You may encounter them indoors and can release them outside.
Tarantulas have venom, but it does not generally affect people unless you are allergic to it. You may feel a bit of stinging and have slight swelling following a bite. Follow first-aid guidelines and see a doctor if you have a tarantula bite.
Tarantulas live in the Southern and Southwestern United States.
These spiders hunt at night. They do not have venom, but their bites can hurt. Therefore, serious symptoms are minimal.
Most spider bites are harmless, and symptoms will go away after a few days. Seek immediate medical care if you suspect a black widow or brown recluse spider bite. If you have life threatening symptoms, the bite gets worse, or you have an allergic reaction, seek medical care right away.