What Causes Periodic Hiccups
Hiccups result from involuntary spasmodic contractions of the diaphragm and intercostal muscles followed by abrupt glottic closure, producing the characteristic "hic" sound—a phenomenon that is physiologically normal and exists even in utero. 1
The Hiccup Reflex Arc
Hiccups operate through a three-component reflex arc that explains why they occur periodically rather than continuously 2, 3:
- Afferent limb: Sensory input travels via the phrenic nerve, vagus nerve, and sympathetic nerves 2, 3
- Central processing unit: The midbrain modulates and coordinates the reflex 2, 3
- Efferent limb: Motor signals travel to the diaphragm and intercostal muscles to produce the spasm 2, 3
The periodic nature reflects the intermittent triggering of this reflex arc rather than continuous stimulation.
Most Common Triggers in Healthy Individuals
Gastroesophageal reflux disease (GERD) is the single most important cause of hiccups, particularly when they occur within approximately 10 minutes after eating, suggesting gastric distention triggers lower esophageal sphincter opening. 4, 1
Other common benign triggers include 3, 5:
- Gastric distention from rapid eating, carbonated beverages, or overeating 4
- Temperature changes affecting the esophagus (very hot or cold foods/drinks) 5
- Alcohol consumption 4
- Sudden excitement or emotional stress 3
Why Hiccups Are Self-Limited
The periodic, self-limited nature of benign hiccups reflects transient irritation of the reflex arc that spontaneously resolves once the triggering stimulus dissipates 1, 5. This distinguishes normal hiccups (lasting minutes to hours) from pathological persistent hiccups (>48 hours) or intractable hiccups (>2 months), which indicate underlying organic disease requiring investigation 1, 3.
Neurotransmitter Involvement
The central neurotransmitters implicated include GABA, dopamine, and serotonin, while peripheral neurotransmitters are epinephrine, norepinephrine, acetylcholine, and histamine 2. This complex neurochemical modulation explains why hiccups occur episodically rather than as a sustained phenomenon—the reflex requires repeated triggering rather than continuous activation.
When to Worry
Do not dismiss hiccups lasting beyond 48 hours as benign—persistent hiccups warrant investigation for serious underlying causes including myocardial ischemia, stroke, tumors along the reflex arc, pericarditis, or medication effects (particularly ACE inhibitors, anti-Parkinson drugs, anesthetics, steroids, and chemotherapy agents). 4, 6, 3