Astragalus is a herbaceous perennial plant of the pea family and is most commonly used for immune enhancement. Most research on astragalus has focused on its immunostimulatory activity and its seemingly remarkable ability to restore the activity of a suppressed immune system. Clinical trials as well as pharmacological data provide evidence for its usefulness in the prevention of the common cold and as an adjunct to cancer therapies. It is may be useful as a complementary treatment during chemotherapy, radiation therapy and immune deficiency syndromes. Astragalus is used to strengthen the immune system over time, building resistance to illness and disease. Echinacea may be used in conjunction with astragalus to provide an extra short term boost in immunity. Astragalus is often used in combination with other botanicals and is very seldom used as a single agent. Pharmacological research of astragalus in combination with ligustrum (Ligustrum lucidum) provides evidence for activity against cancers of the breast, cervix and lung.