Anxiety or stress-related difficulty swallowing: This is often the most common reason for trouble swallowing pills, especially in individuals without a history of swallowing difficulties with food or liquids. The anxiety can cause muscle tension, making it hard to swallow pills.

Esophageal dysmotility: Conditions like achalasia or diffuse esophageal spasm can cause difficulty swallowing, including pills. However, these conditions usually also cause difficulty swallowing food.
Gastroesophageal reflux disease (GERD): While primarily causing heartburn, GERD can lead to esophageal irritation and potentially difficulty swallowing pills due to esophageal spasms or strictures.
Dysphagia due to medication side effects: Certain medications can cause dry mouth, altered taste, or other side effects that might make swallowing pills more difficult.

Esophageal cancer: Although rare, esophageal cancer can present with progressive difficulty swallowing, starting with solids and potentially pills. It's crucial to investigate any new onset of dysphagia.
Stenosis or stricture of the esophagus: Narrowing of the esophagus due to scar tissue can cause significant difficulty swallowing. This could be due to chronic GERD, caustic ingestion, or other causes.
Neurological disorders (e.g., Parkinson's disease, stroke): These conditions can affect the coordination and function of swallowing muscles, leading to difficulty swallowing pills and other substances.

Eosinophilic esophagitis: An allergic inflammatory condition of the esophagus that can cause difficulty swallowing due to esophageal narrowing or spasms.
Scleroderma: A chronic autoimmune disease that can lead to esophageal dysmotility and fibrosis, causing swallowing difficulties.
Oral or pharyngeal conditions (e.g., oral cancer, tongue tie): Although less common, conditions affecting the mouth or throat can also lead to difficulty swallowing pills.