Most girls start their periods between the ages of 12 years and 13 years, but some start earlier or later.

When you first start having your period, it may last only a few days. Your first few periods may be very light. You may only see a few spots of reddish brown blood. Anywhere from 2 to 7 days is normal.

A menstrual cycle is counted from the first day of bleeding in one month to the first day of bleeding in the next month. The average menstrual cycle is about 28 days, but cycles that are 21–45 days also are normal. It may take 6 years or more after your period starts for your cycle to get regular.

If you track your period every month, you may notice a pattern. It may become easier to tell when you will get your next period. Check online or on your smart phone for apps that can help you track your period.

To track your period on a calendar, mark the first day your bleeding starts on a calendar with an "X." Put an X on each of the following days that you have bleeding. Count the first "X" as day 1. Keep counting the days until you have your next period.

Pads are used to soak up the menstrual flow. Tampons and menstrual cups catch the flow from inside your vagina. Pads, tampons, and menstrual cups can be used at different times. Some also can be used together.

Pads are worn inside your underwear to collect your menstrual flow. They come in different sizes, styles, and thicknesses. Some have extra material on the sides called "wings" that fold over the edges of your underwear to help keep the pad in place and give better protection. A thinner, shorter version of a pad is a "panty liner." Some girls wear panty liners on the last days of their periods when the flow is light or on days when they think their periods will come.

Change your pad at least every 4–8 hours or whenever it seems full or feels wet and uncomfortable. Some girls change their pads each time they urinate.

Some tampons have a plastic or cardboard applicator tube that helps slide the tampon in place. Some tampons do not have applicators and are inserted with just your fingers. A short string attached to the end of the tampon hangs out of your vagina to help you remove it later.

Just like pads, tampons come in different sizes for heavier and lighter periods. The tampon package will tell you how much fluid it will absorb. A "super" tampon, for example, is thicker and is meant for heavy flow. A "slim" or "junior" tampon is slender and is meant for lighter flow.

You should change your tampon at least every 4–8 hours. Leaving a tampon in for a long time has been linked to toxic shock syndrome. When your flow is heavier, you may need to change it more often.

Menstrual cups are made of plastic or rubber. They are inserted into the vagina to catch the menstrual flow. You remove and empty the cup every 8–12 hours. Some cups are used only once and thrown away. Others can be washed and reused.

Some girls have a cramping pain in the lower abdomen or back or breast tenderness just before and during their periods. Others get headaches or feel dizzy. Some get nausea or diarrhea.

To help ease cramps, you can try the following:

• Take ibuprofen or naproxen sodium (if you do not have an allergy to aspirin or severe asthma). Always follow the directions on the bottle about how much to take.
• Exercise.
• Place a heating pad, heat wrap, or other source of heat on your abdomen or lower back.
• If these problems do not go away after treatment or if you cannot go to school or do your normal activities, you should talk to your doctor

Amenorrhea means not having a period. It is normal for some girls not to start their periods until age 16 years. But you should see your doctor if you have not started your period by age 15 years. You also should see your doctor if you have started your period but it then stops for more than 3 months.

If you are bleeding so much that you need to change your pad or tampon every 1–2 hours or if your period lasts for more than 7 days, you should see your doctor See your doctor right away if you are light-headed, dizzy, or have a racing pulse.