Headaches from ArA??? First ive heard of that. I dont really see why it'd cause headaches. Not calling you a liar, just not seeing why there'd be a connection.
Edit: Hold on while I retype.
There is a connection because ArA converts to Prostaglandins in the body. There are several studies which show no increase in headaches in normotensive patients due to increase PGF2-a (the one ArA is most known for increasing) but several that show increase in headaches where an increase in prostaglandin E2 is seen. If my reading skills are any good then this is my understanding of the process.
Ara intake --> PGh2---> (some other stuff happens) --> PGE2 (can cause headaches)
Biochem is not my forte so i'm not too sure on how relevant the data is, but anecdotally, headaches are a common side effect, but one that seems to decrease as the duration of the run lengthens.
Many supplements have unwelcome side effects (Forskolin and increased bowel movements as one example) but these generally are reported to subside. If headaches do seem to come on and you cannot tolerate them; I recommend lowering the dose and assessing from there, then increasing dose slowly.