According to conventional medical wisdom, menopause-related hot flashes fade away after six to 24 months. Not so, says a new study of women going through menopause. Hot flashes last, on average, for about seven years and may go on for 11 years or more.The hormonal roller coaster that comes with the end of a woman’s childbearing years can trigger a range of symptoms.ot so, says a new study of women going through menopause. Hot flashes last, on average, for about seven years and may go on for 11 years or more. The hormonal roller coaster that comes with the end of a woman’s childbearing years can trigger a range of symptoms.