This information is for people who have heavy periods. It tells you about the combined contraceptive pill, a treatment used for heavy periods. It is based on the best and most up-to-date research.
Does it work?
We don't know. There isn't enough information to be certain. But some women do lose less blood during their periods when they take the combined contraceptive pill.
What is it?
The pill is called 'combined' because it contains man-made forms of two female hormones: oestrogen and progesterone.
There are lots of different brands of this type of contraceptive pill, including:
Although the combined pill is used mainly to prevent pregnancy, it can also be used to treat:  
You usually take the pill for 21 out of the 28 days of your menstrual cycle (this is time leading up to and including your period). You get your period when you stop taking the pills. Then you start taking the pills again after seven days.
The National Institute for Health and Clinical Excellence (NICE), the government body that decides which treatments should be available on the NHS, says that the combined contraceptive pill is one of the first treatments women should consider having for heavy periods. 
How can it help?
The combined pill may reduce your bleeding.
It may help about as much as other commonly used treatments, such as danazol and the non-steroidal anti-inflammatory drugs mefenamic acid and naproxen. But there's not enough research to know for certain.  
How does it work?
The combined pill changes the levels of two hormones that are important to your menstrual cycle: oestrogen and progesterone. This shift in hormone levels stops you releasing eggs and getting pregnant. It also stops the lining of your womb (the endometrium) thickening during the second half of your menstrual cycle.
This means that, at the end of your cycle, there is less womb lining to come away, so you lose less blood during your period. 
To read more about what happens during your period, see What are heavy periods?
Can it be harmful?
Milder side effects of the combined contraceptive pill include feeling sick, getting headaches, changes in your weight, and breast tenderness, or an increase in the size of your breasts. 
The pill can also affect your mood. You may feel depressed or have a lower sex drive. 
The pill has been linked to some more serious side effects.  For example, it can increase your risk of a blood clot and some kinds of cancer. These side effects can be worrying, but they're rare. It's also worth remembering that the combined contraceptive pill actually helps protect against some types of cancer.
To read more, see Side effects of combined contraceptive pills.
How good is the research on the combined contraceptive pill?
There isn't much research on whether the pill helps heavy periods. Although there are some studies, they are small and not very good.     So we can't say for certain whether the pill helps.
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