Causes of Acid Reflux & Heartburn

What causes acid reflux?

Acid reflux occurs when the muscle surrounding the juncture of your esophagus (throat) and stomach, the Lower Esophageal Sphincter (LES), either doesn’t close properly or opens too often. This allows stomach acid to flow backwards or ‘reflux’ into the esophagus.

The LES may not function properly for various reasons. These include:

  • Certain prescription medications.
  • An increase in stomach pressure caused by overeating, pregnancy or being overweight.
  • Smoking, as it relaxes the LES.


Other factors associated with acid reflux don’t affect the LES but cause an increase in stomach acid. For instance, acidic food and beverages like fried or fatty food, tomato-based meals, alcohol, and coffee can cause excess stomach acid. Stress has also been linked to general digestive upset, including increased acidity in the stomach.

What causes heartburn?

Heartburn is caused by acid reflux, and describes the burning sensation that can radiate from your abdomen to as high as your throat.