What causes someone to collapse?

Written by: Dr Amanda Varnava
Edited by: Nicholas Howley

Collapsing is surprisingly common – at least 1 in 2 people will suffer a collapse at some point in life. We asked leading consultant cardiologist Dr Amanda Varnava what causes someone to collapse and what a GP should do to investigate the problem.

What are the main causes of collapse?

There are three main causes of collapse: simple fainting, heart problems, and seizures.

When a doctor investigates the cause of collapse, they will always perform an ECG to monitor the activity of your heart. It’s vital that any cardiac issues are identified as they can be potentially life-threatening.

In most cases, the doctor can get a good idea of the kind of problem you’re experiencing from the initial investigation:

Signs that it’s a cardiac problem

The doctor will suspect a cardiac problem if:

  • you collapse during exertion (i.e during physical activity)
  • you collapse without any warning symptoms
  • you injure yourself from collapsing
  • you have a family history of premature heart disease or sudden death

You’ll be referred to a specialist cardiologist for further assessment. During this time you are likely to be advised not to drive.

Signs that it’s a seizure

The doctor will suspect seizure if you have:

  • a sense déjà vu before collapsing
  • major shaking as soon as you collapse
  • blood in your mouth or confusion after collapsing

In this situation, you are likely to be referred to a neurologist.

Signs that it’s just simple fainting

Fainting is not as worrisome as the other causes discussed above, but still something that should be investigated and mitigated where possible. Your doctor is likely to suspect simple fainting if:

  • you feel dizzy, sick, or clammy before you collapse
  • you get ringing in your ears or blurred vision before you collapse
  • you take quite a while (at least fifteen minutes) to recover
  • you collapse after a hot bath, when standing, or in hot environments

Usually a diagnosis of simple fainting can be made on these symptoms alone. Treatment in this situation will mainly involve advice on keeping very well hydrated and avoiding caffeine. Provided you don’t suffer attacks while driving, you’ll still be able to drive.

By Dr Amanda Varnava

Dr Amanda Varnava is a leading London-based consultant cardiologist and head of the Department of Cardiology at Imperial College Healthcare Trust. Her area of expertise is in inherited cardiac conditions, sudden death, collapse and sports cardiology. She established the Inherited Cardiac Conditions specialist clinic at Hammersmith Hospital, Imperial College Healthcare Trust and leads the Pregnancy and Heart Disease Service at Watford General Hospital. She is an expert in sports cardiology and one of the few national experts in this field. Dr Varnava sees many athletes (both professional and amateur) and is the cardiologist to a number of professional football teams including Arsenal, Watford, and Fulham FC.


Dr Varnava qualified from Oxford University and then St Bartholomew's Hospital with triple honours. She then undertook specialist cardiology training at some of the leading cardiac centres in the UK, including St George's Hospital, Royal Brompton Hospital, and The London Chest Hospital. Dr Varnava took up her consiltant post in 2005. She has a very active research programme and is an Honorary Senior Lecturer at Imperial College London. Dr Varnava's research into inherited cardiac conditions is published in leading cardiology journals, and she regularly speaks at national and international conferences.

Dr Varnava runs a paediatric screening service at St Mary's Hospital and sees patients from 12 years onwards in her private practice. 

View Profile

Overall assessment of their patients

  • Related procedures
  • Heart attack
    Hypertension (high blood pressure)
    Heart failure
    Injury valves
    Heart murmur
    Ambulatory electrocardiogram (Holter)
    This website uses our own and third-party Cookies to compile information with the aim of improving our services, to show you advertising related to your preferences as well analysing your browsing habits. You can change your settings HERE.