Low mood lasting weeks: causes, red flags and where to get help

Depression is more than sadness. It affects thinking, energy, sleep, appetite and how you experience pleasure, and it can develop after difficult events, in the context of long-term stress, or with no obvious trigger. Physical illness and some medicines can contribute, which is why a medical check is useful.

• Depression (major depressive episode), triggered by stress, loss, relationship or work problems, or occurring without obvious cause.

• Anxiety disorders, often co-existing with low mood.

• Adjustment reactions to life events, bereavement or illness.

• Seasonal pattern (winter low mood) and postnatal depression.

• Perimenopause and menopause, and hormonal changes.

• Medical conditions: underactive thyroid, anaemia, B12 or vitamin D deficiency, chronic pain, diabetes and sleep apnoea.

• Alcohol and drug use, and medicines such as some steroids, beta blockers and isotretinoin.

• Bipolar disorder, dementia in older adults and, rarely, brain or hormonal disease.

Thoughts of self-harm or suicide, feeling hopeless, being unable to function at work or home, hearing or seeing things others do not, very high energy or elevated mood alternating with low mood, severe weight loss or not eating, and a history of bipolar disorder need urgent professional help.

• Call 999, go to A&E, or call Samaritans on 116 123 (free, 24 hours) now if you are thinking of ending your life or have harmed yourself. In England you can also call NHS 111 and choose the mental health option.

• Same-day GP: feeling unable to cope, severe hopelessness, or not eating or sleeping for days.

• GP within days to a week or two: low mood lasting two weeks or more, affecting daily life.

• Support services: talk to someone you trust and consider self-referral to NHS Talking Therapies.

The doctor asks about mood, interest, sleep, appetite, energy, concentration, guilt, thoughts of self-harm, anxiety, life events, alcohol and drug use, medicines, past episodes and family history. They use a questionnaire such as PHQ-9, check physical health and may offer blood tests.

• PHQ-9 and GAD-7 questionnaires: to measure symptom severity.

• Blood tests: full blood count, thyroid function, B12, folate, vitamin D, glucose, kidney and liver function.

• Risk assessment: asking directly about self-harm and suicidal thoughts.

• Screening for bipolar disorder and substance use where relevant.

• Sleep and physical health assessment.

Stay active, even with short daily walks, keep regular meals and sleep, reduce alcohol, stay in contact with people and set small achievable goals. Talk to someone you trust. Cognitive behavioural therapy and other talking therapies are effective, and antidepressants help many people with moderate to severe depression; these are prescribed after assessment and should not be stopped suddenly.

In England you can self-refer to NHS Talking Therapies without seeing a GP. Private psychiatry, psychology and counselling are available directly, and many employers provide support services.