What are the causes of hiccups?

Causes of Hiccups

Hiccups result from disruption anywhere along a complex reflex arc involving peripheral receptors (phrenic, vagus, and sympathetic nerves) and the brainstem, with gastroesophageal reflux disease (GERD) being the most common pathological cause of persistent hiccups 1.

Understanding the Reflex Arc

The hiccup mechanism involves:

• Afferent pathway: Vagus nerve, phrenic nerve, and sympathetic fibers from chest organs, abdomen, ear, nose, and throat
• Central processing: Hiccup center in the brainstem/midbrain
• Efferent pathway: Phrenic nerves causing diaphragmatic and intercostal muscle contraction with immediate laryngeal closure 2

Any irritant—physical, chemical, inflammatory, or neoplastic—along this pathway can trigger hiccups.

Classification by Duration

• Acute hiccups (< 48 hours): Usually benign, self-limited
• Persistent hiccups (> 48 hours): Suggest underlying pathology requiring evaluation
• Intractable hiccups (> 2 months): Require comprehensive workup 2

Major Etiologic Categories

Gastrointestinal Causes (Most Common)

GERD is the predominant cause and should be the first consideration 1. Other GI causes include:

• Gastric and duodenal ulcers
• Gastritis and esophagitis
• Gastric distention
• Pancreatitis
• Distal esophageal spasm 3
• Hepatitis and enteritis 4

Upper GI investigations (endoscopy, pH monitoring, manometry) should be included systematically in persistent cases 5.

Cardiovascular Causes

• Myocardial infarction/ischemia: Hiccups can be an atypical presentation of cardiac ischemia through vagus nerve irritation 4, 6
• Pericarditis

Central Nervous System Causes

• Stroke
• Brain tumors and space-occupying lesions
• Traumatic brain injury
• Meningitis 4
• Inflammatory disorders 2

Peripheral Nerve Irritation

• Phrenic nerve: Tumors, goiter, chest surgery/injury 4
• Vagus nerve: Otolaryngologic diseases, thoracic pathology 4

Infectious Causes

• Tuberculosis (including miliary TB) 6
• Herpes infection 2

Metabolic/Systemic Causes

• Renal failure 5
• Electrolyte imbalances

Neoplastic Causes

• Mediastinal masses (esophageal tumors, Hodgkin lymphoma, neuromas) 7
• Prostate cancer 5
• Any tumor along the reflex arc 2

Drug-Induced Hiccups

Multiple medications can cause hiccups 7, 8:

• Corticosteroids and benzodiazepines (most frequently reported) 8
• Anti-Parkinson drugs
• Anesthetic agents
• Chemotherapeutic agents
• Antibiotics (amphotericin, erythromycin, sulfonamides, aminoglycosides) 7

However, evidence for direct causation remains insufficient for most drugs 8.

Benign/Transient Causes

• Gastric distention (overeating)
• Alcohol intake 5
• Carbonated beverages 9
• Sudden temperature changes

Clinical Approach

For persistent hiccups beyond 48 hours, the workup should prioritize:

1. First-line: Assume GERD and initiate proton pump inhibitor (PPI) therapy with appropriate GI consultation 1
2. If symptoms persist: Explore other etiologies systematically based on the reflex arc
3. Cardiovascular evaluation: Especially in patients with cardiac risk factors, as hiccups may herald myocardial ischemia 4, 6
4. Neurological assessment: For central causes if peripheral causes excluded
5. Medication review: Consider drug-induced etiology and trial withdrawal of suspected agents 7

Important Caveats

• Persistent hiccups are never "just hiccups"—they signal underlying pathology requiring investigation 1
• The most serious causes (MI, stroke, malignancy) can present with hiccups as the primary or sole symptom
• Upper GI pathology is so common that endoscopic evaluation should be routine in persistent cases 5
• In high-risk and elderly patients, extensive workup is mandatory even for seemingly benign presentations 6