Indigestion has a number of different causes, but it's rarely due to a serious, underlying condition.
It's normal for your stomach to produce acid, but sometimes this acid can irritate the lining of your stomach, the top part of your bowel (duodenum) or your gullet (oesophagus).
This irritation can be painful and often causes a burning sensation. Indigestion may also be due to the lining of your digestive system being overly sensitive to acid, or the "stretching" caused by eating.
Indigestion can also be triggered or made worse by other factors. Some of these are explained below.
You may have indigestion if you take certain types of medication. Some medicines, such as nitrates (taken to widen your blood vessels) relax the oesophageal sphincter (ring of muscle between your oesophagus and your stomach), which allows acid to leak back up.
Other medicines, such as non-steroidal anti-inflammatory drugs (NSAIDs), can affect your digestive tract and cause indigestion.
Do not take NSAIDs, such as aspirin and ibuprofen, if you have stomach problems, such as a stomach ulcer, or have had this in the past. Children under 16 years of age should not take aspirin.
Never stop taking a prescribed medication unless you are told to do so by your GP or another qualified healthcare professional who is responsible for your care.
If you are very overweight, you are more likely to experience indigestion because of increased pressure inside your stomach (abdomen).
The increased pressure, particularly after a large meal, may lead to acid reflux into the oesophagus.
Stress or anxiety
If you regularly experience feelings of stress or anxiety, this can contribute to symptoms of indigestion.
Read some relaxation tips to relieve stress.
A hernia occurs when an internal part of the body, such as an organ, pushes through a weakness in the surrounding muscle or tissue wall.
A hiatus hernia occurs when part of your stomach pushes up into your diaphragm (the sheet of muscle under your lungs). It may partially block refluxed stomach acid clearing from your oesophagus, leading to heartburn.
Helicobacter pylori infection
Helicobacter infection is very common. It may lead to stomach ulcers or, rarely, stomach cancer. In most cases, however, it does not cause any symptoms at all.
Some people may get bouts of indigestion from helicobacter infection and, in these cases, getting rid of the bug with antibiotics (eradication) will help. However, many cases of indigestion are not caused by helicobacter, and in these cases eradication will not get rid of symptoms.
Gastro-oesophageal reflux disease (GORD)
Gastro-oesophageal reflux disease (GORD) is a common condition and one of the main causes of recurring indigestion. It's caused by acid reflux, which occurs when the oesophageal sphincter fails to prevent stomach acid from moving back up into your oesophagus.
A little bit of acid reflux is normal and rarely cause any symptoms. It becomes GORD when large amounts of reflux occur, and the sensitive lining of your oesophagus may get inflamed by repeated irritation from stomach acid. This can lead to heartburn, the sensation of regurgitation or painful swallowing.
A stomach ulcer is an open sore that develops on the inside lining of your stomach (a gastric ulcer) or small intestine (a duodenal ulcer). If you have a stomach ulcer, you may have indigestion as a symptom.
Stomach ulcers form when stomach acid damages the lining in your stomach or duodenum wall. In most cases, the lining is damaged as a result of an H pylori infection (see above).
In rare cases, recurring bouts of indigestion can be a symptom of stomach cancer.
Cancer cells in your stomach break down the protective lining, allowing acid to come into contact with your stomach wall.