Menstrual flow can be quite variable in girls, especially the first year that it starts. It is very common for girls to have a few cycles and then none for a month or two, and then start again. Eventually, most girls settle into a pattern of having their periods about every 28 to 35 days. The flow can last 3 to 7 days. There are some days, usually the first two days, when the flow is heavy, and other days when it is very light.

Most young girls start out wearing pads because they are easy to use. A pad should be changed every three or four hours, and possibly more often on days when the flow is heavy. The other reason to change them often is that an odor can develop over time.

There is no right age for starting to use tampons -- it's an individual decision. For some girls who have a small vaginal opening, it may be difficult and uncomfortable to insert a tampon. For these girls, it's probably a good idea to wait until they've matured a bit more and the vaginal opening has stretched out.

A girl also needs to be mature enough to feel comfortable inserting a tampon into the vagina. They also have to be responsible enough to make sure to change the tampon frequently as there is a higher risk of developing toxic shock syndrome if tampons are left in for long periods of time. Additionally, some young girls may "forget" that it's there, and be at risk for other types of infections.

For many girls, the use of tampons early on makes them more comfortable continuing all of their regular activities (such as swimming) and less likely to see their periods as being something that restricts them. Thus for an active, responsible adolescent there is no reason she can't use tampons right away. Girls this age should go to their doctor on a regular basis (yearly), though there is no reason to specifically go just because she's started her period, unless she is having problems with it.