Complementary therapy is and should only be used with regular medical therapy. It is not suppose to be used as a replacement or instead of standard medical care.

A complementary therapy is one which you take along with your main treatment.

An alternative is one which you take instead of main treatment

There are many complementary herbal therapy treatments available for cancer patients. Many utlize Echinacea which helps boost the immune system.

A surgical problem which has progressed far beyond its initial stages might not respond to complementary medicine.

an effective treatment for promoting relaxation and overall well-being, and as an adjunct, or complementary therapy in treating some disorders and illnesses