Norethisterone is a synthetic form of the naturally occurring
hormone in your body called progesterone. Therefore, it mimics the action of
progesterone and can delay your period when taken 3 days before your period is due to start. The body sheds
your womb lining, which is what your period consists of; when the progesterone
levels in your normal monthly cycle begin to fall. By increasing the
progesterone levels we can delay this process.
Even though norethisterone mimics progesterone, a hormone
also in contraceptive pills, it cannot be used as birth control. It also cannot
be used in conjunction with the combined contraceptive pill but can be used
with the mini (progesterone only) pill. Norethisterone should not be taken by
pregnant or breastfeeding women.