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Heart attack

Dr Lynn Thomas, OStJ, BSc, MB.BS, MA, FRCPClinically reviewed: 28/04/2025

A heart attack happens when the supply of blood to part of the heart is suddenly blocked, usually by a blood clot. Find out what to do and how to perform first aid.

What is a heart attack?

A heart attack happens when the supply of blood to part of the heart is suddenly blocked, usually by a blood clot. You can make a full recovery following a heart attack, but this may depend on how much of the heart is affected.

Signs and symptoms

Someone having a heart attack may:

  • have crushing pain in the centre of their chest, that may spread to their jaw, and down one or both arms

  • be breathless or gasping for breath

  • be sweating profusely

  • experience pain similar to indigestion

  • collapse without warning

  • complain of dizziness

  • have pale skin and their lips may have a blue tinge

  • have a rapid, weak, or irregular pulse

  • have a feeling of impending doom.

What to do

  1. 1

    Call 999 or 112 for emergency help straight away and tell them you think someone is having a heart attack.

  2. 2

    Help move the casualty into a comfortable position. The best position is on the floor, with their knees bent and their head and shoulders supported.

    • You could place cushions behind them or under their knees.

  3. 3


    Give them one aspirin tablet (300mg) and ask them to chew it slowly.

    • Do not give aspirin to the casualty if they are under 16 or if they are allergic to it.

  4. 4

    Ask the casualty to take their own angina medication, if they have some.

  5. 5

    Keep monitoring the casualty’s level of response until emergency help arrives.

    • If they become unresponsive at any point, prepare to start CPR.

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