Hi Sarah, I'm someone else who has taken a lot of Doxy to very good effect - I do not have, nor have had Lyme - and had no side effects from it aside from a slight upset if I forgot to eat with it. Doxycycline has been the single most important and useful drug I have taken. I have long thought that my bacterial infections have been blessings in disguise as they led to my understanding of the usefulness of doxycycline. Last year I undertook a course of pulsed Doxy which was helpful. Some symptoms which were very troublesome have not reappeared... yet. Finally, the three variables that coincided with my 85% remission of symptoms were: removal of ovaries and no HRT for 9 months, introduction of Xanax for sleep and long courses of antibiotics for a bizarre chronic bladder infection. So, who knows... I hope you have a similar experience. Could happen Eyes crossed!