Hiccups happen due to involuntary spasms or contractions of the diaphragm, the muscle that separates the chest from the abdomen and plays a key role in breathing. When the diaphragm suddenly contracts, it causes a sharp intake of breath, and the vocal cords close briefly, producing the characteristic "hic" sound
. This spasm can be triggered by irritation or stimulation of the nerves that control the diaphragm, mainly the vagus and phrenic nerves
. Common triggers include:
- Eating too quickly or overeating
- Drinking carbonated beverages or alcohol
- Swallowing air (e.g., chewing gum, smoking)
- Sudden temperature changes
- Emotional stress or excitement
- Consuming spicy or hot foods
Sometimes, hiccups may occur without an obvious cause. In rare cases, persistent or long-lasting hiccups can be caused by nerve damage, central nervous system disorders, metabolic issues, or certain medications
. In summary, hiccups are caused by an involuntary contraction of the diaphragm muscle, followed by a sudden closure of the vocal cords, often triggered by irritation of nerves or various physical or emotional stimuli
