prodrom

A prodrome, or prodromal phase, is a set of early signs and symptoms that precede the full onset of a disease or disorder. The term stems from Greek roots meaning “before” and “a running course,” reflecting the idea that these features mark the approach of an illness. Prodromal features are often nonspecific and can vary widely between individuals and conditions, serving as an alert that pathology is developing rather than providing a definitive diagnosis.

Prodromal symptoms occur in many contexts. In infectious diseases, a prodrome may include fever, malaise, headache, fatigue, or respiratory symptoms that precede the characteristic rash or other hallmark features. In neurology and psychiatry, prodromes describe early changes before an attack or the emergence of a disorder; for example, a schizophrenia prodrome may involve social withdrawal, reduced functioning, and subtle cognitive changes, while migraine sufferers may experience yawning, mood changes, or fatigue hours or days before headache onset. Parkinson’s disease and other neurodegenerative conditions can also have prodromal signs such as loss of smell, constipation, or sleep disturbances years before motor symptoms appear.

Clinical significance lies in early recognition and potential intervention. Identifying prodromal signs can prompt earlier testing, monitoring, or treatment, possibly altering disease trajectories in some conditions. However, prodromes are not disease-specific and may overlap with benign phenomena, so they must be interpreted in the broader clinical context.

See also: prodrome, prodromal.