Acid Indigestion Causes, Symptoms and Treatment

What is Acid Indigestion?

Acid indigestion is not a clearly defined condition. It is a common term attributed to several upper gastrointestinal conditions including gastritis, peptic ulcers and gastroesophageal reflux disease (GERD). All these conditions are affected or caused by stomach acid either irritating or ulcerating the lining of the esophagus, stomach or duodenum (first part of the small intestine).

Acid indigestion is a common term that is also used to describe non-ulcer dyspepsia. Other frequently used terms for acid indigestion are a sour stomach or upset stomach.

Causes of Acid Indigestion

Acid Reflux

In most cases, acid indigestion is used to describe acid reflux (acute) or gastroesophageal reflux disease (chronic). In these cases, the acidic stomach contents flow backward into the esophagus. The esophagus is not as well equipped to deal with acid as the stomach and duodenum. It depends on the lower esophageal sphincter (LES) to prevent the entry of stomach acid into the esophagus. Saliva is secreted in large amounts in an attempt to neutralize any acid that does enter the esophagus.

Some of the causes of acid reflux include :

  • Acute
    • Overeating, sleeping or lying flat immediately after eating, carbonated beverages, caffeinated drinks and alcohol. Read more on Acid Reflux Causes.
  • Chronic
    • Lower esophageal sphincter dysfunction, hiatal hernia, impaired esophageal motility, delayed gastric emptying and increased intra-abdominal pressure. Read more on Stomach Reflux Causes.

Signs and Symptoms of Acid Reflux

  • Heartburn (burning chest pain)
  • Regurgitation
  • Waterbrash (sudden accumulation of large amounts of saliva in the mouth)
  • Throat irritation

Refer to other common symptoms below that may occur with all causes of acid indigestion.


The stomach has a protective barrier of mucus to prevent the acidic secretions from irritating the stomach lining. If this is compromised, the stomach acid can cause inflammation and even ulceration. The more common causes of gastritis is Helicobacter pylori infection and the use of NSAID drugs. Both these causative factors increase gastric acid secretion and disrupt the protective mucus barrier within the stomach.

Signs and Symptoms of Gastritis

Refer to other common symptoms below that may occur with all causes of acid indigestion.

Peptic Ulcer

A peptic ulcer may arise in anywhere in the upper gastrointestinal tract although most peptic ulcers occur in the duodenum. The duodenum deals with incoming chyme by diluting and neutralizing it with a mix of water and bicarbonate ions secreted by the pancreas. In addition, the digestive hormone secretin also reduces gastric acid secretion and gastric emptying.

Most cases of peptic ulcer occur as a result of :

  • Duodenal ulcers : H.pylori infection
  • Stomach ulcers : H.pylori infection, use of NSAIDs
  • Esophageal ulcers : acid reflux (discussed above) and H.pylori infection

Signs and Symptoms Peptic Ulcers

The symptoms are similar to gastritis symptoms and tend to aggravate after eating.

In severe ulceration, there may be upper gastric bleeding which may present as blood in the vomit (hematemesis) or black tarry stools (melena).

Refer to other common symptoms below that may occur with all causes of acid indigestion.

Symptoms of Acid Indigestion

The following symptom are common to most causes of acid indigestion.

Treatment of Acid Indigestion

Most of the causes of acid indigestion will respond to antacids as the primary cause or aggravating factor is stomach acid. For chronic cases, acid suppressing drugs like proton pump inhibitors and H2-blockers may also help to prevent and treat the condition. Refer to Stomach Acid Medication.

Other treatment measures are discussed under :

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