A social media hoax about what to do if you suffer a heart attack appears to be doing the rounds again, almost two years after it first surfaced.

The hoax centres on the idea of "cough CPR". It advises that if you suffer a heart attack when alone, you can help yourself by "coughing repeatedly and very vigorously".

People are urged to take a deep breath before each cough and ensure that the cough is "deep and prolonged". This must be repeated every two seconds "until help arrives, or until the heart is felt to be beating normally again".

However heart experts worldwide have debunked this idea.

According to the Irish Heart Foundation, there is "no medical evidence to support the use of cough CPR" and it does not endorse this practice.

It advises that in the event of someone experiencing chest pain or finding someone collapsed, the most important thing to do is call the emergency services on 999 or 112. If the person is not breathing, they require CPR.

The British Heart Foundation also emphasised that there is no medical evidence to support "cough CPR".

It urged people who come across this advice on social media to "avoid spreading it further and consider letting the person who posted it know that there's no truth in it".

Meanwhile, the American Heart Association also said that it does not endorse this practice.

"As noted in the 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, ‘cough CPR' is not useful for unresponsive victims and should not be taught to lay rescuers," it said.

For more information on CPR, click here.