Most swollen spider bites can be treated at home with basic first aid: clean the bite, ice it, elevate it, and take an over-the-counter pain reliever or antihistamine. Swelling from a typical spider bite peaks within the first 24 to 48 hours and resolves within a few days. The key is knowing what to do right away, what medications actually help, and which warning signs mean the bite needs professional attention.
First Aid for a Swollen Spider Bite
Start by washing the bite with mild soap and water. This is the single most important step because it removes bacteria from the skin surface and reduces your risk of a secondary infection, which is actually more common than serious venom reactions. After cleaning, apply an over-the-counter antibiotic ointment to the bite. Reapply it three times a day for the first few days.
Next, apply a cool compress to bring down swelling. Use a clean cloth dampened with cold water or wrap ice in a towel. Hold it on the bite for 15 minutes, then remove it for the rest of the hour. Repeat this cycle as needed. Placing ice directly on bare skin can cause frostbite, so always use a barrier. If the bite is on your hand, arm, foot, or leg, elevate that limb above your heart when you’re sitting or lying down. This helps fluid drain away from the swollen area.
Medications That Reduce Swelling and Pain
Two types of over-the-counter medication address spider bite swelling from different angles. An antihistamine (like diphenhydramine or cetirizine) reduces the swelling and itching driven by your body’s immune response to the venom. Ibuprofen tackles both pain and inflammation. If you can’t take ibuprofen due to stomach issues or other medications, acetaminophen will manage pain but won’t reduce inflammation directly.
You can use an antihistamine and a pain reliever together since they work through different pathways. Follow the dosing instructions on the package and avoid exceeding the recommended daily limits, especially with acetaminophen.
Home Remedies That Don’t Work
You’ll find recommendations online for baking soda pastes, vinegar compresses, drawing salves, and other folk remedies. None of these have scientific evidence supporting their use for spider bites. Some can actually irritate broken skin and slow healing. The Mayo Clinic’s treatment protocol sticks to soap, water, antibiotic ointment, cold compresses, and elevation. That’s the evidence-based playbook, and adding unproven treatments introduces unnecessary risk of skin irritation or allergic reaction on already-damaged tissue.
Normal Healing vs. Signs of Infection
A typical non-venomous spider bite follows a predictable pattern. You’ll see redness and swelling around the puncture site that peaks in the first day or two, then gradually fades over the course of a week. Mild itching during healing is normal.
A bacterial skin infection looks different. It produces a poorly defined area of redness that keeps expanding outward from the bite rather than shrinking. The skin feels hot to the touch, and the tenderness worsens instead of improving. Red streaks extending away from the bite indicate the infection is spreading along your lymphatic system. Fever, chills, fatigue, or swollen lymph nodes near the bite suggest the infection has moved beyond the skin. If you notice two or more of these signs (expanding redness, warmth, increasing swelling, worsening tenderness), the bite likely needs antibiotics prescribed by a doctor.
Brown Recluse and Black Widow Bites
Most spider bites in North America come from harmless species and resolve with basic home care. The two exceptions worth knowing about are brown recluse and black widow bites, which produce distinctly different symptoms.
Brown Recluse Bites
Brown recluse bites are painless at first, which means you may not notice one for hours. The bite site becomes sensitive and red about three to eight hours later, often with a burning sensation. It may develop a bullseye appearance or turn bluish from bruising. Within three to five days, an ulcer can form at the bite site if venom has spread into the surrounding tissue. In severe cases, the skin breaks down over one to two weeks and creates a wound that can take months to fully heal. A thick black scab typically covers the wound by the three-week mark. The majority of brown recluse bites, though, heal within three weeks without severe complications.
Severe symptoms beyond the bite itself include fever, chills, dizziness, vomiting, rash, and difficulty sleeping. These suggest the venom is causing a systemic reaction and require prompt medical care.
Black Widow Bites
Black widow venom is neurotoxic rather than tissue-destroying. Pain develops within minutes and can spread through the entire body. Within a few hours, you may experience severe abdominal muscle cramps, muscle spasms, difficulty breathing, high blood pressure, and nausea or vomiting. Partial limb paralysis and delirium are possible in serious cases. Black widow bites need emergency medical attention because the systemic effects can become life-threatening. Antivenom exists and is used for critically ill patients.
When Professional Treatment Is Needed
Certain situations call for medical care beyond home first aid. Seek attention if swelling continues expanding after 48 hours, if you develop a blister or open sore at the bite site, if you notice a bullseye or target-shaped lesion, or if you have systemic symptoms like fever, muscle pain away from the bite, breathing difficulty, or severe abdominal cramping.
For bites that become necrotic (where the tissue dies and forms an open wound), professional treatment involves removing the dead tissue, applying antimicrobial treatments, and managing the wound as it heals from the inside out. Some cases require more advanced interventions like negative pressure wound therapy to promote tissue growth. These wounds heal slowly and need ongoing medical supervision.
If it’s been five or more years since your last tetanus booster, a spider bite is a good reason to get one updated. The CDC classifies animal and insect bites as dirty wounds, and people who haven’t had a tetanus shot within five years should receive a booster. If you’ve never completed a full tetanus vaccination series or don’t know your vaccination history, your doctor may also recommend an additional protective injection.