As with any other oil, neem oil will wash off with water. This is true whether you use it as a spot treatment or apply it regularly all over the body. If you do want it to stay on the skin longer, add some aloe vera juice or olive oil to the mixture. Aloe vera contains enzymes that break down proteins and helps heal burns while olive oil soothes irritated skin. There are several varieties of neem trees grown worldwide for their many useful products. The Indian neem tree (Azadirachta indica) is particularly rich in nutrients including vitamin C, calcium, iron, and zinc. It has long been used in India as an insecticide and fungicide and today is also used in animal health products and as a natural dye. The Chinese neem tree (Neem fructus) is widely cultivated in China for its fruit which contain high levels of antioxidants. The seed oil is used in cosmetics because of its moisturizing properties while the seed powder is used as a spice and flavor enhancer in cooking.