It dramatically increases the chances of the person dying because it stops you pushing down on the chest, which is about the only life-saving thing that actually might work in that extreme situation.
Chest compression has been proved to be the most effective technique in various studies - and yet doctors continue to recommend mouth-to-mouth as part of emergency first-aid care for heart attack patients.
So why do they? It may be because they treat all sudden and life-threatening attacks the same - and, of course, they're all different, despite having superficial similarities.
A person who has almost drowned or taken a drugs overdose may look like a heart attack victim - but there's one big difference. In these cases, the victim has usually stopped breathing, and so mouth-to-mouth combined with chest compression is absolutely the right thing to do.
But most heart attack victims are still breathing very lightly, or gasping, and so mouth-to-mouth is not only unnecessary, it may also increase the chances of death.
(Source: The Lancet, 2007; 369: 882-4).
E-news broadcast 22 March 2007 No.344 [Subscribe]