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What to do if…
you develop swelling or rapid weight gain with shortness of breath, especially when lying down

Produced and maintained by PanicStation.org Published: Last reviewed: Editorial policy UK guide

Short answer

Call 999 now if you have severe difficulty breathing, cannot get words out, have a tight or heavy chest, become suddenly confused, turn very pale, blue or grey, or pass out and do not recover normally. Otherwise, sit upright and seek urgent medical assessment now rather than waiting for a routine appointment.

Do not do these things

  • Do not lie flat if this makes your breathing worse.
  • Do not push through physical activity or walk around to test your breathing.
  • Do not take extra water tablets or change any medicine unless a clinician or an agreed care plan tells you to.
  • Do not assume the swelling is ordinary weight gain, bloating, poor fitness or anxiety.
  • Do not drive yourself to A&E if you are severely breathless, faint, confused or becoming worse.
  • Do not wait until morning if the symptoms are new, worsening quickly or preventing you from lying down.

What to do now

  1. Call 999 immediately if you are gasping, choking, unable to get words out, have a tight or heavy chest, have pain spreading to your arms, back, neck or jaw, become suddenly confused, turn very pale, blue or grey, or pass out and do not recover normally.
  2. Call 999 if one leg has become painful or swollen and you also have shortness of breath or chest pain.
  3. Sit upright in a supported position that makes breathing easiest. Avoid lying flat and stop any activity that worsens the breathlessness.
  4. If no emergency sign applies, ask your GP for an urgent appointment now. If you cannot reach your GP, call 111 in England, NHS 24 on 111 in Scotland, or NHS 111 Wales on 111. In Northern Ireland, contact your local GP out-of-hours service when your surgery is closed.
  5. State clearly that you have swelling or rapid unexplained weight gain with shortness of breath, especially when lying down. Say when it started and whether it is worsening.
  6. Tell the clinician immediately about chest discomfort, faintness, a fast or irregular heartbeat, coughing up blood, frothy pink phlegm, reduced urination, or swelling that is mainly in one painful leg.
  7. Keep your medicines or an up-to-date medication list nearby. Note approximately how much weight you have gained, over how many days, and where the swelling is visible.
  8. Take your usual medicines only as prescribed. Follow any existing heart-failure action plan, but do not delay urgent help.
  9. Ask someone to stay with you if possible. Keep your phone nearby and follow any instructions given by the clinician or emergency call handler.

What can wait

You do not need to identify the cause, make long-term diet or exercise changes, buy monitoring equipment, or decide whether your medicines should change. Detailed tracking and future treatment decisions can wait until after you have contacted urgent medical help.

Important reassurance

These symptoms do not confirm one particular condition, but the combination needs prompt assessment. Seeking urgent help for breathing difficulty with swelling or sudden weight gain is appropriate.

Scope note

This guide covers immediate first steps only. Tests, treatment choices and ongoing monitoring may require assessment by a GP, urgent-care clinician, hospital team or relevant specialist.

Important note

This is general medical information, not a diagnosis or a substitute for advice from a qualified healthcare professional. Follow the instructions given by emergency services or the clinician assessing you.

Additional Resources

Closely connected guides that may be useful during the same situation or its immediate aftermath.

About this guide

This guide was produced and is maintained by PanicStation.org using its published editorial process. Official and specialist sources are checked where relevant, and AI-assisted tools may be used for drafting, organisation, and consistency checks. The site operator remains responsible for publication, revision, and removal decisions.

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