The duration of a depressive episode varies widely depending on the type of depression, individual factors, and whether treatment is received. Here's a clear breakdown:

Major Depressive Disorder (MDD): An untreated major depressive episode typically lasts 6–12 months on average, with most people experiencing symptoms for 6–8 months before natural remission. About 50% recover within 6 months, 70–80% within a year. However, 20–30% develop chronic depression lasting 2 years or more.

Persistent Depressive Disorder (Dysthymia): This milder but chronic form lasts at least 2 years in adults (1 year in children/adolescents), often fluctuating but rarely fully remitting without treatment.

Bipolar Disorder: Depressive episodes in bipolar I/II typically last 2–6 months if untreated, though they can be shorter (weeks) or longer (over a year) depending on cycling speed.

Seasonal Affective Disorder (SAD): Episodes usually begin in fall/winter and resolve in spring, lasting 4–5 months annually.

Postpartum Depression: Typically peaks at 3–6 months postpartum and resolves within 12 months for most, but can persist longer without intervention.

With Treatment:

• Antidepressants: 50–60% see significant improvement within 6–8 weeks; full remission often by 3–6 months.
• Therapy (CBT/IPT): Similar timeline, with 60–70% responding within 12–16 weeks.
• Combination treatment: Fastest recovery 70–80% remit within 3–4 months.

Key Factors Affecting Duration:

• Early intervention shortens episodes dramatically.
• Stress, trauma, substance use, or co-occurring anxiety prolongs them.
• Recurrence: 50% experience another episode within 2 years; 80% within 5 years.

Bottom Line: Without help, expect 6–18 months. With proper treatment, most recover within 3–6 months. If symptoms persist beyond 2 weeks and impair daily life, seek professional help immediately early treatment can cut duration by 50% or more.