Depression is categorised as mild, moderate, or severe. The severity of depression is classed by the number and intensity of symptoms, and impairment they produce. As a general guide: mild depression is five or fewer symptoms, where the patient can still work and socialise moderate depression is five or six symptoms, with impaired function severe depression has at least seven symptoms (or fewer symptoms that are especially intense), along with almost no usual function and the risk of self-harm Clinicians often use standardised questionnaires to quantify the severity of depression and track it over time.