Most spider bites heal on their own with basic first aid: cleaning the wound, applying cold, and keeping the area elevated. The majority of bites resolve within three weeks, and only a small number of spider species can cause serious harm. Here’s what actually works, what doesn’t, and when to get help.
Immediate First Aid Steps
The first thing to do is clean the bite with mild soap and water. This removes bacteria from the skin surface and reduces the chance of infection. Next, apply a cool cloth or a clean cloth filled with ice over the bite for 15 minutes each hour. Cold slows the spread of venom components in the tissue and brings down both pain and swelling. If the bite is on your hand, arm, foot, or leg, elevate it above heart level when you can.
Keep up the cooling routine for at least the first 72 hours. For bites from venomous spiders like the brown recluse, cold compresses are especially important because the venom’s tissue-damaging activity is temperature dependent. Cooling the area can slow the progression of skin breakdown.
Over-the-Counter Pain and Itch Relief
If the bite is itchy, an oral antihistamine like diphenhydramine (Benadryl) or cetirizine (Zyrtec) can help. For pain and inflammation, standard over-the-counter options like ibuprofen or acetaminophen work well. A hydrocortisone cream applied to the bite area can also reduce localized itching and redness.
Avoid scratching the bite. Breaking the skin opens a path for bacteria to reach deeper tissue layers, turning a simple bite into a secondary infection.
Home Remedies That Don’t Work
You’ll find plenty of advice online about applying baking soda paste, lemon juice, salt, or activated charcoal to a spider bite. None of these are effective or recommended. The idea behind them is that you can somehow draw out or neutralize the venom, but once venom is injected into tissue, it gets picked up by tiny capillary veins below the skin surface almost immediately. It’s gone before any topical substance could pull it back out.
For the same reason, you should never cut into a bite to try to remove venom or encourage bleeding. This won’t push venom back out. All it does is create an open wound that invites bacterial infection into the tissue layers beneath the skin.
What a Normal Healing Timeline Looks Like
Most spider bites follow a predictable course. In the first few days, you’ll notice redness, mild swelling, and some discomfort at the site. For the vast majority of bites, this peaks within three to five days and then fades. By three weeks, most bites are fully healed.
Brown recluse bites can follow a different path. If the spider injected a small amount of venom, discomfort typically resolves within a few days. But if the venom spread beyond the immediate bite area, an ulcer can develop at the site within the first week. In severe cases, the skin around that ulcer breaks down between 7 and 14 days after the bite, creating a wound that can take several months to heal completely. These cases sometimes require specialized wound care or skin grafting.
Signs That Need Medical Attention
Most spider bites don’t require a trip to the emergency room, but certain symptoms signal something more serious. Get medical care right away if you experience any of the following:
- Severe abdominal cramping or rigidity. This is a hallmark of black widow bites and is sometimes mistaken for appendicitis.
- Difficulty breathing or swallowing. This can indicate a systemic allergic reaction.
- A growing wound at the bite site. Expanding tissue damage suggests significant envenomation, likely from a brown recluse.
- Spreading redness or red streaks moving outward from the bite, which can signal a developing infection.
- Severe pain that doesn’t respond to over-the-counter medication.
If you know or suspect the bite came from a black widow or brown recluse, seek medical care even before serious symptoms develop. Antivenom exists for black widow bites and is typically given as a single dose. Elderly patients are more vulnerable to black widow venom and are more likely to need antivenom early.
Tetanus and Infection Risk
Spider bites are puncture wounds, and puncture wounds fall into the category of dirty or major wounds for tetanus risk. If your last tetanus vaccination was five or more years ago, or if you’re not sure when you had one, a booster is recommended. If you’ve been vaccinated within the last five years and completed the full primary series, you don’t need one.
Watch the bite site for signs of secondary bacterial infection over the following days. Increasing redness, warmth, pus, or red streaks spreading from the wound all suggest bacteria have gotten into the tissue. This is a separate problem from the venom itself and would need antibiotics to treat. Keeping the wound clean and avoiding scratching or cutting the bite are the best ways to prevent this.
Bites From Dangerous Spiders
Only two spider groups in the United States cause medically significant bites: widow spiders (black widows and relatives) and recluse spiders (primarily the brown recluse). Almost all other spiders either can’t penetrate human skin or deliver venom too mild to cause more than temporary irritation.
Black widow bites tend to cause systemic symptoms rather than local tissue damage. The venom affects the nervous system, producing intense muscle cramping, abdominal pain, and sometimes elevated blood pressure. These symptoms can be frightening but are rarely fatal. Treatment focuses on pain management and, when needed, antivenom.
Brown recluse bites cause local tissue damage rather than widespread body symptoms. The venom destroys skin cells around the bite, and in serious cases this creates a necrotic wound that deepens over one to two weeks. Treatment involves keeping the area cool, elevated, and splinted, along with careful wound care. Early surgical removal of the damaged tissue isn’t recommended because it can worsen outcomes. Instead, doctors wait for the damage to stabilize before considering any surgical repair.