There is current interest in using ginger to fight migraine headaches. It has a small amount of antihistamine and anti-inflammatory action which may be the basis for its effectiveness.
The anecdotal information is that a woman in Denmark took 500 to 600 milligrams of powdered ginger in water at the first sign of a migraine. Relief came within 30 minutes. After a few days of taking powdered ginger, the woman changed to eating the raw form. The amount is not given. Fewer migraines were reported and those that did break through were of less intensity. It seems to reduce nausea also.
Before this information is conclusive, a double-blind experiment needs to be done with a group using ginger and a control group using a placebo.