Most common complication of achalasia is:

Achalasia Rare motility disorder of the esophagus which results from lack of innervation of the lower esophageal sphincter muscles and leads to dilatation of proximal esophagus. Typically with dysphagia, vomiting of undigested food and failure to thrive. Cough can be present in achalasia patients due to aspiration of food or due to airway compression by the dilated esophagus resulting in recurrent pulmonary infections.