Book excerpt: Drawing on indigenous and scientific knowledge of medicinal plants, Traditional Herbal Therapy for the Human Immune System presents the protective and therapeutic potential of plant-based drinks, supplements, nutraceuticals, synergy food, superfoods, and other products. Medicinal plants and their products can affect the immune system and act as immunomodulators. Medicinal plants are popularly used in folk medicine to accelerate the human immune defence and improve body reactions against infectious or exogenous injuries, as well as to suppress the abnormal immune response occurring in immune disorders. This book explains how medicinal plants can act as a source of vitamins and improve body functions such as enhanced oxygen circulation, maintained blood pressure and improved mood. It also outlines how specific properties of certain plants can help boost the immune system of humans with cancer, HIV, and COVID-19. Key features: Provides specific information on how to accelerate and or fortify the human immune system by using medicinal plants. Presents scientific understanding of herbs, shrubs, climbers and trees and their potential uses in conventional and herbal medicine systems. Discusses the specific role of herbal plants that act as antiviral and antibacterial agents and offer boosted immunity for cancer, H1N1 virus, relieving swine flu, HIV and COVID-19 patients. Part of the Exploring Medicinal Plants series, this book is useful for researchers and students, as well as policy makers and people working in industry, who have an interest in plant-derived medications.