I get headaches/ migraines often. usually on the left side, starting right behind my eye. i'm 18. what could be the cause of these?

Cause unknown: Now the first thing you need to do is make sure to see a physician, preferably a headache specialist who will probably do an mri, as well as thorough detailed physical exams and blood work. Assuming you have already had this done. There are a variety of meds which can help to prevent headaches, many patients find taking magnesium daily, or massage can help reduce the severity of the headaches, .

Any number of things: Headaches behind the eye can be troubling. First, you need to be under the care of a headache specialist - a neurologist. They will make sure the proper diagnostic studies are done. Possible treatable causes include internal problems with the nose, nerve impingement above the eye, or other problems that imaging - a ct or MRI - will be able to diagnose.