Since the 7th century, Sweet Annie has been used to control fever and malaria. Sweet Annie is used to control malaria because the herb contains the chemical artemisinin. According to malariasite.com, artemisinin helps to suppress trophozoites, the feeding-stage parasites of malaria. Because the trophozoites are suppressed, the malaria cannot spread throughout the body.
In addition, Sweet Annie has been used to control fever. According to altmd.com, the herb works by regulating the body's internal thermostat, the hypothalamus. The herb essentially turns down the body's metabolic generation of heat, much like how aspirin or ibuprofin works to reduce a fever.
In addition to being used as a medical supplement, Sweet Annie is used largely in arts and crafts. According to herbcompanion.com, Sweet Annie makes an excellent filler for bouquets and other flower arrangements. The herb can also be made into wreaths. The sweet fragrance of the herb lends to its usefulness as a craft-plant since the scent is not overpowering, so it tends to complement the other components in the craft.