Propranolol
"I have been on propranolol since mid-January 2013. If I remember correctly, it began working within a few weeks. I am on 80mg (can't remember if I worked up to that or not, was in rehab at the time so not everything is crystal clear) and have found that my daily headaches have pretty much completely disappeared. I read that the normal dose is between 80 and 240mg, but I obviously want to be on as little as possible, especially considering possible side effects. But 80mg works for me. Rarely I get one and ibuprofen is enough to relieve it. This medicine was truly life-changing for me. I have had chronic headaches from the age of 9! Point being, if you are considering this medication to help prevent headaches, I highly recommend you try it."