Hello, I have never done this before, but after taking Doxy for a long time for lymes disease I have been off of it for a while and some of the lymes symptoms were coming back so I started again on Doxy. I have started having chest pains and a constant headache. I just thought I would look it up and found this site. I am glad to know the chest pains are from the doxy and also the heartburn. I think I will take my chances with the Lymes.