A wide range of drugs is associated with dysphagia, although it may not always be possible to pinpoint a direct cause to a medicine.^6,11 Sites of drug activity exacerbating dysphagia include:⁶

• central – usually sedating
• central with peripheral activity – reducing saliva production
• neuromuscular
• locally on the mucosa
• unexpected or unexplained mechanism.

In general, medicines can cause or contribute to swallowing difficulties in three broad categories:^6,11

• a side effect, eg dry mouth (xerostomia) with anticholinergic drugs
• a complication of an intended therapeutic effect, eg long-term high-dose corticosteroids causing wasting of skeletal muscle in the upper oesophagus impairing the swallowing reflex
• a medicine-induced oesophageal injury (MIOI) with local irritation, such as due to an acidic medicine.

For some medicines, damage can be caused by the duration of contact, which will increase if the medicine is taken while lying down. If taken immediately before sleeping, the risk of reduced peristalsis and decreased saliva secretions can have an impact if the medicine has not cleared the oesophagus, especially if the medicine is not taken with sufficient fluid.¹¹

Oesophageal damage is more likely in the elderly, due to the higher likelihood of polypharmacy and needing more doses as well as decreased oesophageal motility and saliva production.