Why do we hiccup? It might be an ancient reflex for drinking milk.

Health · Published 3 October 2026 Swipe more like this →

In short: Hiccups are more than just an annoying spasm. While transient bouts are often triggered by eating too fast or drinking carbonated beverages, persistent cases can signal serious underlying health issues. Scientists suspect this involuntary reflex may have evolved to help young mammals swallow milk without getting air in their stomachs.

A hiccup is an involuntary contraction of the diaphragm, a muscle essential for breathing. This action is governed by a reflex arc involving the vagus and phrenic nerves. When these nerves are irritated, the diaphragm contracts suddenly, followed by the glottis closing within about 35 milliseconds, which produces the characteristic sound. While most hiccups are transient and harmless, they can become persistent—lasting over 48 hours—or intractable, meaning they last longer than a month. These long-term cases are often linked to complex medical conditions, including gastrointestinal diseases, central nervous system disorders like Parkinson’s, or even certain tumors.

One prominent evolutionary hypothesis suggests that hiccups are a remnant of the suckling process in mammals. By creating suction in the chest, the reflex helps move air out of the stomach, allowing infants to consume more calorie-rich milk. This theory is supported by the fact that hiccups are common in infants and decrease in frequency as we age. Another perspective suggests an even older origin, proposing that hiccups are a vestigial motor reflex from amphibians, who use a similar gulping motion to move water and air across their gills. This would explain why the neural pathways for hiccuping develop in the fetus before those required for lung ventilation.

For those suffering from chronic singultus, the impact on daily life is profound. Data from the Heidelberg Registry of Chronic Singultus, which tracked 131 patients between October 2022 and March 2025, revealed that 90% of those with chronic hiccups experience fatigue, while 80% suffer from sleep disorders. The registry also highlighted a high burden of comorbidities, with 75% of patients reporting gastrointestinal issues. Because the condition is rare and the underlying mechanisms are not fully understood, medical treatment remains challenging. While various folk remedies exist, there is a lack of high-quality evidence for any specific cure, leaving patients to navigate a difficult path toward relief.

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