The most effective drugs so far arrived in the early 1990s. These medications, known as triptans, include Imitrex, my current drug of choice. While they have brought temporary relief, they have not prevented or reduced the overall number of headaches.

Now we may have true cause for hope.

At least four large companies are holding clinical trials to study something called monoclonal antibody therapy. This therapy uses genetically engineered antibodies to stimulate the immune system and attack a nasty compound that is elevated in the brain during migraine headache pain. The treatment would be injected periodically. It has had excellent results in early trials, and could be available within a few years. “Not only is this the most hopeful thing on the horizon,” said Dr. Joseph Safdieh, a neurologist at Weill Cornell Medical College who is not involved with the trials, “it is the only hope on the horizon.”

But why has it taken so long to find a fix for an ailment that so many millions suffer from? The answer may be that what looks like one syndrome could actually be a symptom of a number of different conditions.

According to Dr. Steven B. Graff-Radford, the director of the Headache and Orofacial Pain Program at Cedars-Sinai Medical Center in Los Angeles, “most migraine sufferers are undiagnosed or given the wrong diagnosis.” He said, “They go to their general doctor — when they should be seen by specialists — and are told they have sinus or tension headaches, which are treated with antibiotics or psychological management, when they have other kinds that should be treated another way.”

There are countless possible causes of headaches. “I find, almost as soon as I am recognizing the trigger in my midst — an artificial scent or bright light or barometric pressure — it’s too late and I have to ride the wave,” Cara Levine, an artist in Northern California, told me last year. Crippling, psychedelic migraines like Ms. Levine’s are often hereditary, and she recently discovered that her grandmother also apparently suffered from them.