A person who has dysphagia may have difficulty swallowing solid foods or liquids because they are unable to move food from the mouth into the stomach due to problems with muscle control or weakness of the throat muscles. Swallowing can be difficult when people have a stroke, head injury, Parkinson's disease, Alzheimer's disease, multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), or other neuromuscular conditions that affect eating and drinking abilities. Dysphagia can also occur following surgery.