Cuscuta is classified as a Yang tonic herb, but because of its sweet taste and flat nature, it is both a Yang tonic and a Yin tonic, and belongs to the class of herbs that are flat tonic to Yin and Yang. Cuscuta seeds are often used in health care and are used to nourish kidney and yang, and can be used for soreness and weakness of the waist and knees, and impotence of tendons and bones caused by deficiency of kidney and yang. There is a famous formula called “Wu Zi Yan Zong Wan” in which the main herb is Cuscuta, together with Wu Wei Zi, Fructus Lycii, Raspberry and Psyllium, it is a famous Chinese herbal medicine for tonifying kidney yang and benefiting kidney essence. Cuscuta can also be used for fetal restlessness caused by deficiency of kidney yang, so it is a herbal medicine with a calming effect on the fetus, and for diarrhea caused by deficiency of both spleen and kidney. Cuscuta is the seed of the southern cuscuta of the spinach family. When soaked in water, the germ will be exposed, just like the silk that comes out, so it is called cuscuta. In addition, to teach you a little knowledge, cuscuta seeds can be used externally to treat vitiligo. You can use cuscuta seeds to make wine and apply it externally with a cotton swab dipped in the wine after 14 days to treat vitiligo to some extent. Although cuscuta is a flat tonic for yin and yang, it is relatively inclined to tonic yang, so people with yin deficiency and internal heat, and those with actual heat in their bodies, should still use cuscuta with caution.