Spider Bites: What to Do, What’s Normal and When to Get Help

Most spiders can’t even break human skin, and most bites cause only mild pain and redness. A handful of species around the world can cause serious illness. And many skin lumps blamed on spiders turn out to be infections, so knowing the signs matters.

Imagine waking with a painful red lump on your thigh. You’re sure a spider got you in the night. Over two days it grows, becomes hot and fills with pus. A nurse examines it and explains it’s actually a skin abscess, a bacterial infection that needs treatment, not a spider bite at all.

First aid for a spider bite

• Wash the area with soap and water
• Apply a cold pack to reduce pain and swelling
• Take simple painkillers if needed
• If safe, take a photo of the spider; it helps identification

Spiders that can cause serious illness

Examples include widow spiders (found on most continents), recluse spiders (mainly the Americas) and the Sydney funnel-web in Australia, where a pressure bandage and immobilisation are part of first aid and antivenom is available. Local poison information services can advise on species in your area.

But when should you get help?

Call your emergency number for severe pain spreading from the bite, muscle cramps, sweating, vomiting, breathing difficulty, or if the bite may be from a dangerous species. See a doctor or nurse if the area becomes increasingly red, hot, swollen or pus-filled, if a dark or ulcerating patch develops, or you develop a fever.

Sources: US Centers for Disease Control and Prevention (Venomous spiders), NHS (Insect bites and stings), Healthdirect Australia (Spider bites), World Health Organization. This guide is for general information and does not replace advice from your own nurse, doctor or poison centre.