Repressing your emotions effects one person: you. However, you
need to consider that they things you do and the ways you act can
affect other people as well. Repressing your emotions can certainly
affect the way you act, and thus other people can be affected as
well.
It is generally considered unhealthy to repress one's emotions.
This can put stress on you and have detrimental consequences for
your health. If you are repressing your emotions on purpose, this
can be dangerous and it is healthy to find an outlet for this
emotion. If you cannot find an outlet or stop repressing emotion,
you may want to try visiting a psychologist or psychiatrist, who
may be able to help you out.