Lately topical Tretinoin has been shown in numerous studies to cause Idiopathic Intracranial Hypertension aka Pseudotumor Cerebri which is quite intense. My post about this on sca from years ago recieves a many comments to this day from other sufferers. I'll never touch it again despite my adult acne. I wonder how many other people have debilitating potentially blinding brain pressure headaches and don't realize it is caused by this medicine commonly accepted as safe.