Mental health and mental illness are different words. Mental health is overall wellbeing. It means emotional, psychological, and social wellbeing, and it affects how a person thinks, feels, and acts. It also affects how the person handles stress, relates to others, and makes choices. Everyone has mental health, just as everyone has physical health. Mental illness is the term for diagnosable conditions that affect a person's thinking, feeling, or behaviour. Those conditions can significantly affect daily functioning and quality of life. Severity and duration vary. Not everyone will experience a mental illness.
Rethink Mental Illness puts both definitions on one page. The page was read on 15 October 2026 and does not show a revision date.
| Mental health | Mental illness | |
|---|---|---|
| What the word covers | Emotional, psychological, and social wellbeing | Diagnosed conditions that affect mood, thinking, and behaviour |
| Who has it | Everyone | Not everyone |
| What else the page says | It affects thinking, feeling, acting, stress, relationships, and choices | It can affect daily functioning and quality of life. Severity and duration vary |
The wellbeing word applies to everyone. The diagnosed-condition word does not.
Sources
- Rethink Mental Illness, what mental health is and what a mental illness is, page read on 15 October 2026, no revision date shown, Rethink