I am on the 2nd day of doxycycline for a uti (urine test was negative except for step b cells in culture but I've had symptoms for over a week). Today my head felt like it would explode. The pressure was unbelievable- it was the worst headache I've ever had and the only one that's ever involved my entire head. It is starting to subside somewhat 9 hours after taking this morning's pill, but is still painful. Is this a typical headache from doxcycline or could it be intracranial hypertension? I don't want to take the chance of damaging my vision, however, I am allergic to most antibiotics so I don't know what I'd switch to.