Most spider bites can be treated at home with basic first aid: clean the wound, apply a cool compress, and watch for signs of trouble over the next few days. The vast majority of spiders lack venom strong enough to cause serious harm to humans, and a typical bite heals on its own within a week or two. The key is knowing how to care for the bite properly and recognizing the warning signs that mean you need medical help.
Immediate First Aid Steps
As soon as you notice a bite, wash the area with mild soap and water. Apply an antibiotic ointment to help prevent infection, and repeat this three times a day while the bite is fresh. Place a cool, damp cloth or a cloth-wrapped ice pack over the bite for about 15 minutes each hour to bring down swelling and ease pain. If the bite is on an arm or leg, elevate it when you can.
Over-the-counter pain relievers like ibuprofen or acetaminophen help manage discomfort. If the area is itchy, an antihistamine such as diphenhydramine (Benadryl) or cetirizine (Zyrtec) can take the edge off. Resist the urge to scratch, since broken skin invites bacteria and raises the risk of a secondary infection.
How to Tell If a Bite Is Serious
In North America, only two types of spiders pose a real medical concern: black widows and brown recluses. Most other spider bites produce a small red bump similar to a mosquito bite. If you didn’t see the spider, the bite site itself and the symptoms that follow are your best clues.
Black Widow Bites
A black widow’s venom targets your nerve endings, which means the symptoms are felt throughout the body rather than just at the bite. Within an hour or two you may develop severe muscle pain and cramping, especially in the abdomen, shoulders, chest, and back. The abdominal cramping can be intense enough that it’s sometimes mistaken for appendicitis. Other common symptoms include excessive sweating, nausea, vomiting, and tremors. With prompt treatment, most people recover fully within 24 to 48 hours.
Brown Recluse Bites
Brown recluse bites unfold more slowly. The bite area becomes sensitive and red within three to eight hours, often with a burning sensation. The skin may develop a bullseye pattern or turn a bruised, bluish color. Over the next three to five days, a small ulcer can form at the bite site if the venom has spread. In more severe cases, the skin around the ulcer breaks down between seven and 14 days after the bite, creating a wound that can take months to fully close. The majority of brown recluse bites, however, heal within about three weeks, typically forming a thick black scab before resolving.
When to Get Emergency Help
Certain symptoms after a suspected spider bite warrant immediate medical care. Difficulty breathing or swallowing is the clearest emergency signal. So are a fast heartbeat, fast breathing, severe abdominal rigidity, confusion, dizziness, or feeling faint. Fever, chills, and widespread body aches after a bite also point to a systemic reaction that needs professional treatment.
If you’re able to safely capture or photograph the spider, bring it with you. Knowing the species helps medical staff choose the right treatment quickly. For severe black widow bites, hospitals can administer antivenom, which resolves symptoms in roughly 30 minutes on average. In a review of 163 cases, only 12% of patients who received antivenom needed to be admitted to the hospital, compared with 52% of those who didn’t receive it.
Watch for Signs of Infection
Even a harmless spider bite breaks the skin, and broken skin can let bacteria in. Many “spider bites” that people treat at home are actually bacterial skin infections like cellulitis that develop around the wound. Watch the bite over the following days for skin that becomes increasingly red, hot, swollen, and painful. Blistering, red streaks spreading outward from the bite, or flu-like symptoms with swollen glands are all signs that bacteria have taken hold in the deeper layers of skin.
A spreading infection needs antibiotics. If you develop a high fever, purple patches on your skin, rapid breathing, or feel cold and clammy, that’s a sign the infection is becoming severe and you should seek emergency care right away.
Do You Need a Tetanus Shot?
Spider bites that break the skin can potentially expose you to tetanus, especially if the wound becomes contaminated with dirt or develops dead tissue. CDC guidelines categorize necrotic wounds, like those a brown recluse bite can cause, as “dirty or major wounds.” If you’ve completed your tetanus vaccine series and your last booster was less than five years ago, you’re covered. If your last shot was five or more years ago and the wound looks dirty or is developing dead tissue, a booster is recommended. Anyone with an unknown or incomplete vaccination history should get one regardless of wound type.
Normal Healing Timeline
A typical, non-venomous spider bite follows a predictable path. You’ll see redness and mild swelling for the first day or two, with gradual improvement over the next week. The bump may itch as it heals. Most ordinary bites are fully resolved within one to two weeks without any special treatment beyond basic first aid.
Brown recluse bites take longer. Expect the site to look worse before it looks better, with color changes and possible ulceration in the first week. The three-week mark is the benchmark for most brown recluse bites to heal. Severe cases with significant skin breakdown can take several months and sometimes leave a scar. If a bite wound isn’t improving after a week, or is actively getting larger, have it evaluated by a healthcare provider rather than continuing to manage it at home.