Heartburn is a burning feeling in the chest caused by stomach acid travelling up towards the throat (acid reflux). If it keeps happening, it's called gastro-oesophageal reflux disease (GORD).Check if you have acid reflux. The main symptoms of acid reflux are: - heartburn – a burning sensation in the middle of your chest, an unpleasant sour taste in your mouth, caused by stomach acid, You may also have: a cough or hiccups that keep coming back, a hoarse voicebad breathbloating and feeling sick. S