A menstrual period usually lasts 3 to 7 days.
Typical length
A menstrual period lasts 3 to 7 days, with an average of 5. The cycle is usually 21 to 35 days (adults) and 21 to 45 days (teens).
Flow
Heaviest in days 1 to 3. Blood loss totals about 30 to 80 mL.
Normal variation
Periods can be irregular for the first years after the first one (menarche), around age 12.
See a doctor if
- Bleeding lasts over 7 days.
- You soak through a pad or tampon every hour.
- Periods stop for 3 months (without pregnancy).
- Cycles are shorter than 21 or longer than 35 days.
- Severe pain.
Causes of change
Stress, weight change, PCOS, thyroid disease and perimenopause.
Track
Use an app.
Typical period length
A normal menstrual period lasts 2 to 7 days, with most lasting 3 to 5. Cycles run 21 to 35 days in adults, and 21 to 45 days in teens during the first years. Cycle length is counted from the first day of one period to the first day of the next. Blood loss averages about 30 to 40 milliliters in a cycle, and over 80 milliliters is considered heavy.
Flow through the days
The first 2 days are usually the heaviest, followed by lighter flow and spotting. Color can range from bright red to dark brown. Dark brown at the end is older blood leaving the uterus. Small clots up to the size of a coin are normal.
Signs of heavy bleeding
- Soaking through a pad or tampon every hour for several hours.
- Needing to change protection at night.
- Passing clots larger than a quarter.
- A period lasting more than 7 days.
- Symptoms of anemia, like fatigue, breathlessness and dizziness.
Heavy menstrual bleeding affects about 1 in 5 women, according to the CDC, and it is treatable.
Causes of change
- Stress, weight change, exercise and illness.
- Hormonal birth control and intrauterine devices.
- Polycystic ovary syndrome (PCOS), thyroid problems and perimenopause.
- Fibroids, polyps and endometriosis.
- Pregnancy and breastfeeding.
Teenagers
Periods usually start between ages 10 and 15, with an average of about 12.4 years in the US. Cycles in the first 2 to 3 years can be irregular. See a doctor if there is no period by age 15, or three years after breast development began.
When to see a doctor
See a doctor if periods stop for 3 months and you are not pregnant, if cycles are shorter than 21 or longer than 35 days regularly, if bleeding occurs between periods or after sex, or if pain is severe and interferes with daily life.
Tracking
Use a calendar or app to mark the first day of bleeding, flow and symptoms. A record of 3 to 6 months helps a doctor identify patterns.
Tracking and menstrual health facts
A typical period lasts 3 to 7 days, with total blood loss averaging about 30 to 40 ml (about 2 to 3 tablespoons), and over 80 ml is defined as heavy menstrual bleeding. About one in five women reports heavy periods. Cycles are counted from the first day of one period to the day before the next. Cycle length changes in the first years after menarche (average age 12 in the US) and in perimenopause, which usually begins in the 40s. Track dates, flow and symptoms in an app or a notebook so a doctor can see patterns. Iron deficiency anemia is a common result of heavy periods and is treatable with iron and treatment of the cause.
Based on data from ACOG and the CDC
