Spider Bite Identification: Pictures & When to Worry
Educational only. Not medical advice. If you suspect a widow or recluse bite, or have severe symptoms, seek medical care immediately.
Good news first: the vast majority of suspected "spider bites" are harmless and heal on their own. Only a few species cause serious reactions. Here's how to tell an ordinary bite from one that needs attention.
What does a spider bite look like?
A typical spider bite appears as one or two small puncture marks with surrounding redness and mild swelling — often indistinguishable from other insect bites. It may be slightly sore or itchy. Most fade within a week.
Harmless vs. dangerous spider bites
In North America, two groups account for most medically significant bites:
Widow spiders (e.g., black widow)
Bites can cause intense pain, muscle cramps, abdominal stiffness, sweating, and nausea, sometimes spreading from the bite site. Marks may be subtle.
Recluse spiders (e.g., brown recluse)
Bites may start mild, then over hours to days develop a blistering wound that can darken, ulcerate, and heal slowly. Not all recluse bites become severe, but watch the wound closely.
Important: many ulcerating skin wounds blamed on spiders are actually bacterial infections (like MRSA). If a wound is worsening, a doctor's evaluation matters more than identifying the spider.
Caught the spider on camera?
Use the app to identify the spider itself — it covers 1000+ species with danger ratings and key facts.
Identify the spider — free appSpider bite warning signs — seek care if you have:
- Severe or rapidly increasing pain, or muscle cramps and stiffness.
- A wound that blisters, turns dark/purple, or ulcerates.
- Fever, chills, nausea, or sweating.
- A spreading area of redness, warmth, and swelling (possible infection).
- Any trouble breathing or facial swelling — call emergency services.
How to treat a minor spider bite
- Wash with soap and water.
- Apply a cold compress to reduce pain and swelling.
- Keep the area clean and watch it over the next few days.
- Use OTC pain relief or antihistamine as directed.
Compare with other bites in the full identification guide or the visual chart.
FAQ
What does a spider bite look like?
Usually two small puncture marks with redness and mild swelling. Widow or recluse bites can cause stronger pain or a spreading, blistering wound.
How do I know if a spider bite is dangerous?
Warning signs include severe pain, muscle cramps, a darkening or ulcerating wound, fever, nausea, or trouble breathing. Seek care if these occur or you suspect a widow or recluse spider.