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What to do if…
you get a bite or sting and the swelling keeps increasing over hours

Short answer

If swelling is still increasing over hours, get same-day advice via NHS 111 (or urgent GP/pharmacist advice). If you have any breathing/throat symptoms, fainting/confusion, or swelling of lips/tongue/face, call 999 or 112 immediately.

Do not do these things

  • Do not “wait it out” if swelling is spreading quickly, involves the eye/face/mouth/throat, or you feel unwell.
  • Do not scratch, squeeze, or cut the bite/sting.
  • Do not use a tight wrap or tourniquet.
  • Do not exceed the packet directions for antihistamines or painkillers.
  • Do not use home remedies that irritate the skin (for example, powders/pastes/chemicals) or anything that burns.

What to do now

  1. Check for emergency allergy signs (act immediately). Call 999 or 112 if any of these are happening now: trouble breathing/wheezing, throat tightness, trouble swallowing, swelling of tongue/lips/face, blue/grey/pale lips or skin, sudden confusion/drowsiness, fainting, collapse, or feeling suddenly very unwell (often with a widespread itchy/raised rash).
  2. If anaphylaxis is possible and you have an adrenaline auto-injector, use it now. Then call 999 or 112 and say “anaphylaxis.”
    • Lie down (raise legs if you can). If breathing is difficult, you may need to sit up slowly.
    • If symptoms have not improved after 5 minutes and you have a second auto-injector, use it.
    • Avoid standing or walking, even if you start to feel better.
  3. Reduce risk from swelling straight away.
    • Remove rings, watches, tight clothing or shoes from that limb before swelling makes it hard.
    • Rest the area and raise it if it’s an arm/leg.
    • Apply a cold pack (wrapped) or a cold, wet cloth for around 20 minutes if swollen.
  4. Remove anything left in the skin (only what’s on the surface).
    • If it looks like a bee/wasp/hornet stinger, brush or scrape it sideways with a fingernail or the edge of a card. Avoid tweezers (they can squeeze more venom out).
  5. Wash and mark the edge so you can tell if it’s spreading.
    • Wash with soap and water.
    • Draw a pen line around the edge of redness/swelling and write the time; take a clear photo. If the line keeps being crossed over the next few hours, that’s important to report.
  6. Use symptom relief that matches UK self-care advice (if safe for you).
    • Consider an oral antihistamine for itching.
    • Consider paracetamol or ibuprofen for pain (if you can take them).
    • An over-the-counter hydrocortisone cream can reduce itching and swelling—follow the label.
  7. Get same-day help if swelling keeps increasing over hours. Choose the quickest route:
    • NHS 111 (phone or online), especially if symptoms are getting worse or not improving, you feel dizzy/lightheaded, you have tummy pain/vomiting, fever/high temperature or swollen glands, you were stung more than once, you were stung in the mouth/throat/near the eyes, or you’ve had a serious reaction before.
    • A pharmacist (same day) if the area is hot/red/painful/swollen or there’s any weeping/pus (pharmacists can recommend treatments and, where available, supply antibiotics for infected bites/stings).
  8. If symptoms are worsening quickly and you can’t get prompt advice, go to urgent care/A&E. Rapidly increasing swelling, increasing pain with heat/redness, red streaks up a limb, or feeling feverish/unwell should not wait.

What can wait

  • You do not need to identify the exact insect right now.
  • You do not need to decide today whether you “have an allergy” long-term.
  • You do not need to keep checking it by pressing/squeezing; monitor spread with the pen line/photo instead.

Important reassurance

It’s common for bites and stings to look worse before they look better. Some people get a large local reaction where swelling continues to build and may peak around 24–48 hours—that can still be miserable, but it’s different from an emergency whole-body reaction. You’re doing the right thing by seeking help if it’s still expanding, in a risky area (eye/mouth/throat), or you feel unwell.

Scope note

These are first steps for the next few hours. Longer-term decisions (allergy referral, prevention plans, or follow-up if infection is confirmed) can come later.

Important note

This is general information, not a diagnosis. If you’re unsure, contact NHS 111—especially when swelling is continuing to increase, spreading, or you feel unwell.

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