Benefits of Feverfew:  
Headaches/Migraines
Feverfew is believed to help migraine sufferers because of the unique plant chemical it contains, parthenolide, which helps relieve smooth muscle spasms and can combat the widening of blood vessels that occurs in migraines. This effect appears to be backed up by research which shows that Feverfew can reduce the frequency of migraines and reduce symptoms such as nausea, vomiting and sensitivity to light (flashing lights).
Menstrual Cramps:  
Menstrual cramps occur when the lining of the uterus makes large amounts of prostaglandins. When these cells break down during menstruation, the prostaglandins are released. They constrict the blood vessels in the uterus and make its muscle layer contract, causing painful cramps. Because Feverfew has been shown to reduce prostaglandin production, it may be helpful in easing menstrual cramps
Feverfew:  Arthritis—Whist there is conflicting evidence regarding the use of this herb to provide arthritis relief; Feverfew does   possess potent anti-inflammatory properties, which help to prevent swelling and damage to the joints.
There are a group of proteins known as NFkappaB that are a pro-inflammatory signalling pathway which is particularly associated with arthritis. Parthenolide, one of the powerful sesquiterpene lactones found in this herb, is responsible for the bioactive effects of Feverfew, acting as a NFkappaB inhibitor. By inhibiting the process of NFkappaB activation, the severity of the joint erosion can be reduced and the progression of arthritis can be prevented.
Feverfew also acts as an antioxidant, protecting the joint tissues against free radical damage and preventing damage to the membranes lining the surfaces of the bones. This reduces friction between the ends of 2 bones at a place where they meet to form a joint, which may help to provide long-term relief to persons suffering from arthritis.