Therapy literally means "curing, healing" and is attempted remediation of health problems, usually following a diagnosis. In medical field it is synonymous with word "treatment".

Basic three reasons for taking a "treatment" , therapy

1.)  Preventive therapy is a treatment that is intended to prevent a medical condition from accurring.

2.)  Abortive therapy is a treatment that is intended to stop a medical condition from progressing any further.

3.)  Supportive therapy is one that does not treat or improve the underlying condition, but instead increases the patient's comfort.

"And when I am ill, it is He who cures me;" ( Quran, 26, 80)