Perimenopause can start at various ages but most commonly begins in a woman’s 40s. On average, symptoms of perimenopause generally start about four years before menopause, which usually occurs around age 51. Thus, many women experience perimenopause in their mid to late 40s. However, some women may notice changes as early as their mid-30s, especially if they have certain risk factors like smoking or prior cancer treatments. Early perimenopause can start in the late 30s or early 40s, and for some, symptoms may begin even earlier though that is less common. The onset is marked by changes in menstrual cycle length, duration, and flow, as well as symptoms like hot flashes, mood swings, and irregular periods. Perimenopause can last several years, typically between 2 to 8 years, though this varies widely from person to person. In summary:

• Average start: mid to late 40s (around 47)
• Can start as early as mid-30s for some
• Duration typically lasts a few years before menopause
• Early signs include menstrual irregularities and hormonal symptoms

This variability means some women enter perimenopause many years before menopause, while others may experience it closer to their late 40s or early 50s.