The terms heartburn and indigestion are often interchanged, but they are actually two different conditions.
Heartburn (or acid reflux) occurs when acid, which normally sits within the protected lining of the stomach, escapes back up into the oesophagus (food pipe). Because there is no protective coating in the oesophagus the acid irritates and damages the lining. This can cause painful symptoms such as burning, pain (usually behind the breastbone) and a feeling of sickness (often described as a ‘bad taste in mouth’).
Indigestion can also be caused by acid irritation - hence the common confusion. As such, the term ‘indigestion’ encompasses a range of digestive symptoms. These tend to be milder – in comparison with heartburn - but include pain/discomfort in the upper part of the stomach, sickness and nausea and an uncomfortable bloated feeling.