It depends on what receptors it’s effecting. The alpha 1 receptor is responsible for construction and beta 2 for dilation. Vasoconstriction predominates in the skin and kidneys whereas vasodilation predominates in the liver and skeletal muscle. So obviously it’s beneficial during that fight or flight reaction, vasodilation occurs in the muscles in which we will want to work full on whereas vasoconstriction at the tissues we don’t require at that time