To describe the natural history of a condition or disease. To describe the natural history of a condition or disease. To determine effectiveness or cost effectiveness of treatments/services and/or health care products. To measure or monitor safety and harm. To measure quality of care.
According to the NMSS, attacks or flare-ups of symptoms only qualify as exacerbations if: 1  they occur at least 30 days from an earlier flare-up. 2  symptoms last for 24 hours or longer.
Hot flashes often come on suddenly, but how long any single hot flash lasts will vary. Some hot flashes pass after a few seconds, while a long hot flash may go on for more than 10 minutes. On average, hot flashes last about four minutes. How frequently hot flashes occur also varies.