I've used Doxy several times, uneventful, it's Cipro that knocks me for a loop,
and this is the urologist's AB of choice, sorry to say.

Only major side effect was a serious bout of nausea that occured one
morning (i woke up an hr before i usually do to take one) that almost
caused me to passout. <no kidding>  I thought I might have been having
a stroke...and I am only 26.

This was on a second course of doxy (duration: 3 weeks) that I had
taken for my CPPS.  Only symptoms are perineal pain and premature
ejaculation...(no urinary or ejaculation problems).  I think the 2nd
course was a waste as my original actue prostatitis bout was
undermedicated...I was on Doxy for 10 days only originally......6
weeks after this bout the infection and pain set in for good.