Illhealth

Illhealth refers to a state in which a person’s health is below what is expected or desired. It encompasses acute illness, chronic disease, injury, disability, and mental health concerns, and may involve physical, psychological, and social dimensions of well-being. While definitions vary, many health systems align illhealth with conditions that reduce functioning, quality of life, or life expectancy. Illhealth can be temporary or long-lasting and affects individuals across all ages.

Causes range from biological factors such as infections and genetic disorders to lifestyle and environmental factors including diet, physical activity, substance use, pollution, and occupational hazards. Social determinants—poverty, housing, education, access to care—play a crucial role. Mental health conditions frequently occur with somatic illnesses, and together they can worsen overall functioning and treatment outcomes.

Assessment relies on self-reported health, clinical diagnoses, functional ability, disability, and health service use. Illhealth imposes personal and societal costs, including reduced well-being, productivity losses, and greater demand for care and social support. Variations occur by age, sex, ethnicity, and socioeconomic status, and seasonal or regional factors can influence prevalence and care needs.

Prevention and management emphasize timely medical care, chronic disease management, rehabilitation, mental health support, vaccination, healthy lifestyle promotion, and addressing social determinants. Equity of access to health services affects the level of illhealth in a population and is a central concern for health policy and public health programs.