I have pretty bad migraines (though not as bad as some people), and I have tried amitryptyline. My doctor told me that it was such a small dose that I would not have side effects. That was not true for me. It was actually probably the worst period of my life, because I had a very profound reaction, which is that I could not sleep. I got (literally) no more than one or two hours of sleep a night for the couple of months I took it (and even the sleeping pills that my doc then prescribed, because she did not believe that it was the amitryptyline, did not help). Now, I'm not saying that your son is likely to have that reaction, or any serious reaction. But the lesson that I took from my experience is that "prophylactic" long-term medication will be absolutely the last strategy I will employ.
I agree with the others that avoiding triggers is the best strategy. For me, having a strict caffeine schedule (only one cup of tea in the AM) gets me down to only one or two migraines a month. If I pay attention and take OTC pain meds immediately when I feel a migraine coming on, it'll usually nip it in the bud. I usually take both acetaminophen and ibuprofen together, which is fine if you're only taking it once in a while. If I wait until I'm actually in pain, OTC meds won't help at all no matter how much I take.
That said, I also want to ask how often he is having these headaches. Your post makes it sound like they are daily, but if they are daily, they're not likely to be migraines.
