Rose hip is the round portion of the rose flower just below the petals. Rose hip contains the seeds of the rose plant. Dried rose hip and the seeds are used together to make medicine.
Fresh rose hip contains a lot of vitamin C, so some people take it as a source of vitamin C to prevent and treat colds, flu, and vitamin C deficiencies. However, much of the vitamin C in rose hip is destroyed during drying and processing and declines rapidly during storage. Because of this, many rose hip-derived "natural" vitamin C products have actually been fortified with lab-made vitamin C, but their labels may not always say so.
Rose hip is commonly used by mouth for osteoarthritis. It is also used by mouth to treat stomach problems, infections, and obesity and applied to the skin for stretch marks, but there is no good scientific evidence to support these other uses.
In foods and in manufacturing, rose hip is used for tea, jam, soup, and as a natural source of vitamin C.