Acid reflux disease, which is also called gastroesophageal reflux, occurs when the lower sphincter muscle at the end of the esophagus is not able to prevent the backflow of the contents of the stomach into the esophagus. Laryngopharyngeal reflux is another similar condition which is common in infants. In case of laryngopharyngeal reflux, the sphincter muscles located at either end of the esophagus are unable to function properly. As a result, the gastric contents of the stomach (stomach acid) backs up into the back of the throat (pharynx) or voice box (larynx). At times, the stomach acid could even flow back into the back of your nasal airway. This can lead to the inflammation of the tissues in these areas. Heartburn is a characteristic symptom of gastroesophageal reflux. Laryngopharyngeal reflux, which is sometimes referred to as silent reflux, is more likely to cause throat irritation.