Dry heaving, medically known as retching, is an involuntary reflex where the body goes through the physical motions of vomiting without expelling any stomach contents. This experience is typically preceded by nausea, the unpleasant sensation of needing to vomit. Retching is a protective reflex initiated when the body detects a potential toxin or irritant that needs to be expelled.
The Physical Mechanism of Retching
Retching involves a coordinated, involuntary sequence of muscular contractions controlled by the central nervous system. The process begins with rhythmic, spasmodic contractions involving the diaphragm and the abdominal muscles. These muscles act in opposition: the diaphragm pulls downward while the abdominal muscles contract forcefully.
This simultaneous action generates a massive pressure difference between the abdominal and thoracic cavities. The lower esophageal sphincter relaxes, allowing stomach contents to move upward into the esophagus. Unlike actual vomiting, the upper esophageal sphincter and the glottis remain closed, which prevents gastric material from being expelled and protects the airway.
Common Causes and Contributing Factors
Dry heaving often occurs after the stomach has already been emptied, such as during a bout of gastroenteritis or food poisoning. Even with nothing left to expel, neurological signals in the brain’s vomiting center remain active, continuing the reflex action.
Excessive alcohol consumption is a frequent trigger, as the body perceives alcohol and its toxic metabolite, acetaldehyde, as a poison. Alcohol also directly irritates the stomach lining, causing inflammation known as gastritis, which increases the likelihood of the retching reflex.
Hormonal fluctuations in pregnant individuals, particularly during the first trimester, increase sensitivity to nausea and the retching reflex known as morning sickness. Intense physical exertion, especially when performed on a full stomach, can also trigger dry heaving. This occurs because the forceful contraction of the diaphragm during exercise mimics the initial stage of the vomiting mechanism.
Psychological factors like severe anxiety or a panic attack are common causes of dry heaving. The “fight or flight” response causes muscle tension in the gut and throat, which the body may interpret as a need to vomit. Strong or unpleasant smells can also directly activate the chemoreceptor trigger zone in the brain, initiating the retching response.
Recognizing Warning Signs and When to Seek Care
While dry heaving is often temporary, its persistence or association with other symptoms can signal a serious underlying health problem. If retching continues for more than 24 hours for an adult, medical attention should be sought to prevent complications.
The inability to keep down fluids is a significant concern because it indicates a risk of severe dehydration. Signs of dehydration, such as excessive thirst, dry mouth, or producing very little dark-colored urine, require prompt care.
Immediate medical attention is necessary if dry heaving is accompanied by certain red flags. These include severe chest or abdominal pain, which could indicate a tear in the esophagus or acute gastrointestinal issues. Heaving up blood, or material that looks like dark coffee grounds, signals internal bleeding and necessitates emergency care. Other warning signs, such as a severe headache, confusion, fainting, or a rapid pulse, suggest systemic or neurological involvement that must be quickly evaluated.