Knowing the difference between a normal reaction and a dangerous one can save a life. Here are the warning signs of a severe allergic reaction and what to do.
The vast majority of bites and stings cause only local symptoms that settle on their own. But in a small number of people, the body reacts far more strongly — and a severe allergic reaction, called anaphylaxis, is a medical emergency. Recognising it quickly matters more than identifying which insect was responsible.
Normal vs. allergic reaction
A normal reaction is limited to the area of the bite or sting: pain, redness, swelling, and itching that improve over hours to days. A large local reaction is a bigger patch of swelling around the site — uncomfortable, but usually not dangerous. An allergic reaction is different because it affects the whole body, often within minutes.
Signs of anaphylaxis — call emergency services
Treat any of the following as an emergency and call your local emergency number immediately:
- Difficulty breathing, wheezing, or tightness in the throat or chest.
- Swelling of the lips, tongue, throat, or face.
- Dizziness, sudden weakness, fainting, or collapse.
- A widespread rash or hives spreading well beyond the bite.
- Nausea, vomiting, or stomach cramps together with any of the above.
What to do
- Call your local emergency number right away — don't wait to see if it passes.
- If the person has an adrenaline auto-injector (such as an EpiPen), help them use it as prescribed, then still get emergency care.
- Help them sit up if breathing is hard, or lie down with legs raised if they feel faint.
- Stay with them and be ready to give CPR if they stop breathing.
When to see a doctor
Even without an emergency, see a doctor if you've had a large or worsening reaction, if you've ever had a whole-body reaction to a sting before (you may need an allergy assessment and an emergency plan), or if a bite shows signs of infection. If you know you're allergic, carry your prescribed medication and make sure those around you know how to help.
FAQ
How fast can a severe reaction start?
Anaphylaxis can begin within minutes of a bite or sting. That's why you should act immediately rather than waiting to see whether symptoms settle.
I only got swelling around the sting — is that an allergy?
A large patch of swelling limited to the sting area is a local reaction, usually not dangerous. It becomes an emergency when symptoms affect the whole body, like breathing trouble or facial swelling.
