Pubertad y primera regla
Period problems in teens
Revisado: 4 de octubre de 2026
Solo en inglés por ahoraIn the first few years, periods are often irregular and cramps are common. Most of this is normal, but some problems need a doctor. Here is how to tell the difference.
Irregular periods at first
For the first couple of years, it is normal for periods to come at different times. Cycles longer than 38 days are common. Most people's cycles settle into the usual adult range, about 21 to 38 days, within about 3 years. Stress and big weight changes can also affect periods. If you have had sex and your period is late, you could be pregnant. Take a pregnancy test or talk to a doctor or nurse.
Cramps and what helps
Cramps happen when chemicals called prostaglandins make the muscle of the womb (uterus) tighten. They are most common in the first days of a period. A heat pad on your tummy can help. Painkillers such as ibuprofen or naproxen work best if you take them at the first sign of cramps. Ask a parent, carer or pharmacist which medicine is right for you, and follow the leaflet.
PMS: changes before a period
Some people feel different in the days before a period. This is called premenstrual syndrome (PMS). You might feel moody, sad, anxious, irritable or tired. You might also get bloating, backache, sore breasts or spots. Regular exercise, less caffeine and less salt may help. If PMS is so bad that it gets in the way of everyday life, talk to a doctor. If you feel very low or think about harming yourself, tell an adult you trust or get help straight away.
Heavy or long periods
Some teens have heavy periods. Signs include needing to change a pad or tampon every 1 to 2 hours, or periods that last more than 7 days. Passing clots bigger than about 2.5 cm, the size of a large coin, is another sign. Heavy bleeding can cause anaemia, which can make you feel tired, weak or dizzy. In teens, heavy periods are often linked to hormone changes. Sometimes they are a sign of a bleeding disorder, such as von Willebrand disease. This is more likely if you also bruise easily, have nosebleeds that are hard to stop, or have a relative with a bleeding disorder.
When to see a doctor or nurse
See a doctor or nurse if you are 15 and your periods have not started. Also go if they have not started within 3 years of your breasts starting to grow. Go too if your periods are still not regular after 2 years, or if they were regular and then stop for 3 months. Heavy periods, bleeding between periods and cramps that keep you home from school are other reasons to go. Logging your periods in Ciclo can help you explain what is happening. Get urgent help if you bleed very heavily and feel dizzy or faint. Also get urgent help for sudden, severe pain in your lower tummy, especially if you might be pregnant.
This is general information. If your periods worry you, talk to a parent, carer, doctor or nurse. They can help.