Migraines are caused by changes in certain blood vessels of the brain that result in a local disturbance in the action of a specific nerve-activating chemical
Two migraine remedies, drug K and drug L, have exactly the same restorative effects on the local action of this chemical, but L also disrupts the action of several other chemicals in the brain that governmental activity and the body' s metabolism
People whose migraines are treated with L are likely to experience a wider range of effects beyond the cessation of migraines than are people whose migraines are treated with K.