Gastroesophageal reflux disease (GERD): This is often considered the most common cause of persistent hiccups due to the irritation of the nerves that control breathing, which can be affected by stomach acid reflux.

Gastritis or esophagitis: Inflammation of the stomach lining or esophagus can irritate the nerves and cause hiccups.
Laryngitis: Inflammation of the larynx (voice box) can affect the nerves controlling the diaphragm, leading to hiccups.
Pharyngitis: Inflammation of the pharynx (throat) can also irritate the nerves and cause hiccups.
Eating too quickly or drinking too much alcohol: These actions can lead to the swallowing of air, which may irritate the diaphragm and cause hiccups.

Myocardial infarction (heart attack): Although rare, hiccups can be a symptom of a heart attack, particularly in women, and it is crucial not to miss this diagnosis.
Pneumonia: Infections in the lung can irritate the nerves that control breathing, leading to hiccups.
Pancreatitis: Inflammation of the pancreas can cause persistent hiccups due to the proximity of the pancreas to the diaphragm and the potential for nerve irritation.
Stroke or brain tumor: Rarely, hiccups can be a symptom of a neurological issue such as a stroke or a brain tumor affecting the brain's breathing centers.

Sarcoidosis: A condition that can cause inflammation in various parts of the body, including the nerves that control breathing, leading to hiccups.
Multiple sclerosis: A disease affecting the central nervous system that can lead to a wide range of symptoms, including hiccups, due to the demyelination of nerves.
Hydrocephalus: A condition characterized by an accumulation of fluid in the brain, which can put pressure on the brain's breathing centers and cause hiccups.
Inflammatory or infectious diseases affecting the central nervous system: Conditions like meningitis or encephalitis can cause hiccups among other symptoms due to their effect on the brain and its functions.