Most spider bites are harmless and heal on their own within a few days with basic first aid. The immediate priorities are cleaning the wound, reducing swelling with a cool cloth, and watching for signs that the bite came from a more dangerous species. Here’s exactly what to do, step by step.
Immediate First Aid Steps
Start by washing the bite with mild soap and water. Apply antibiotic ointment to the area three times a day to help prevent infection. Then place a cool, damp cloth or a cloth filled with ice over the bite for 15 minutes each hour. This reduces both pain and swelling. If you can, elevate the bitten area above your heart.
For pain, an over-the-counter pain reliever like ibuprofen or acetaminophen works well. If the bite is itchy, an antihistamine (like cetirizine or diphenhydramine) or calamine lotion can help. A hydrocortisone cream is another option for itching and mild inflammation.
Stick with cold rather than heat. Ice constricts blood vessels around the bite, which limits swelling and slows the spread of irritation. Heat can do the opposite.
What a Normal Bite Looks Like
The vast majority of spider bites cause a raised, red, itchy bump that looks similar to a mosquito bite or a bee sting. These symptoms typically last several days and resolve on their own without medical treatment. You may not have even seen the spider, and in many cases what people assume is a spider bite turns out to be another insect bite or a minor skin infection.
Signs of a Brown Recluse Bite
Brown recluse bites are initially painless, which is why people often don’t notice them right away. Over the next two to eight hours, the bite becomes increasingly painful. Early on, you might see two small puncture marks surrounded by redness.
What makes a recluse bite distinctive is how it evolves. The center of the bite turns pale while the outer ring becomes red and swollen. This happens because the venom destroys tiny blood vessels in the area, cutting off circulation to the center. Over the following days, a blister forms and the center shifts to a blue or violet color with a hard, sunken core. Skin breakdown can follow, but this doesn’t typically happen until 7 to 14 days after the bite. The wound eventually heals, but that process can take several weeks.
If you notice a bite that’s getting more painful over hours rather than less, or if a pale center develops surrounded by a red ring, get medical attention. Don’t wait for the skin to break down.
Signs of a Black Widow Bite
Black widow bites feel different from most spider bites almost immediately. Within 15 minutes to an hour, a dull muscle pain spreads outward from the bite and into the body. You may experience muscle rigidity, increased sweating, and abdominal cramping. The pain can be intense and is sometimes mistaken for appendicitis or other abdominal emergencies.
Severe symptoms generally start improving within two to three days, but milder symptoms like muscle soreness and fatigue can linger for several weeks. Treatment at a hospital focuses on pain management with strong pain relievers and muscle relaxants. In cases with severe systemic symptoms, antivenom is an option. A single vial is generally enough to provide relief in both adults and children, though it isn’t used for people with certain allergies, asthma, or past reactions to equine-based products.
When to Go to the Emergency Room
Seek medical care right away if any of the following apply:
- You were bitten by a spider you recognize as a black widow or brown recluse
- You’re not sure whether the spider was dangerous
- You have severe pain or abdominal cramping
- The wound is growing or the surrounding redness is spreading, or you see red streaks extending from the bite
- You’re having trouble breathing or swallowing
Spreading red streaks are a particular warning sign because they suggest the infection is moving into your lymphatic system, which needs prompt treatment.
Capture the Spider if You Can
If the spider is still nearby and you can safely contain it, do so. Place it in a sealed container or zip-lock bag. Even a dead or crushed spider can be identified. Don’t use tape to capture it, as that can damage the specimen and make identification harder. Bring it with you to the doctor or emergency room. Knowing the species changes how the bite is treated.
If you didn’t see the spider, don’t worry. Doctors can often make treatment decisions based on your symptoms and how the wound looks.
Tetanus and Spider Bites
Any puncture wound, including a spider bite, carries a small risk of tetanus. The CDC recommends a tetanus booster if your last tetanus shot was five or more years ago and the wound is dirty or significant, or ten or more years ago for clean, minor wounds. If you don’t know your vaccination history or never completed the primary series, you should get a shot regardless of wound type. If your last tetanus vaccine was less than five years ago and you’ve completed the full series, you’re covered.
What Not to Do
Don’t try to suck out venom, cut the wound open, or apply a tourniquet. These are outdated practices that cause more harm than good. Avoid applying heat to the bite, which can increase swelling and speed up tissue damage in venomous bites. Don’t scratch the area, even if it itches intensely, because broken skin invites infection.
Recovery Timeline
A bite from a common house spider or garden spider typically clears up within a few days. The redness, swelling, and itching peak in the first 24 to 48 hours and then gradually fade. Keep applying antibiotic ointment and watching for infection during this time.
Brown recluse bites take significantly longer. If skin breakdown occurs, healing happens gradually over several weeks as new tissue fills in the wound from the edges inward. Your doctor may refer you to a wound care specialist for larger lesions. Black widow bites, while painful, don’t usually cause lasting skin damage. The systemic symptoms (muscle pain, cramping, sweating) are the main concern, and these typically peak within the first day or two before slowly improving.
For any bite that isn’t improving after 48 hours, or that seems to be getting worse rather than better, have it evaluated. A worsening bite is the single most reliable signal that something beyond basic first aid is needed.