Tetracycline is directly affected to a condition known as Idiopathic Intercranial Hypertension or more commonly known as Pseudotumor Cerebri. It is a very rare neurological condition. It causes Cerebral Spinal Fluid to build up on the brain and therefore causes servere headaches and permanent loss of vision due to pressure built up on the optic nerves. I had taken Tetracycline off and on for many years as a treatment of acne and was always told that the headaches that I had were migraines until I was hosptialized and finally diagnosed correctly by a Neurologist who promptly took me off of the medication. After learning all of this I have done much research and I was already in a high-risk category for this condition and Tetracycline is directly listed on every website as a cause of this condition. I SHOULD HAVE NEVER BEEN PRESCRIBED THIS MEDICATION!!! There are no warnings on the medication to indicate that it causes this condition and my healthcare provider was not aware or she never would have prescribed it to me. Now I live with a VP shunt, blood clots in my brain and constant headaches. What a price to pay to get rid of acne!