QUESTION
I'm a gay man, and although I'm mostly celibate, as part of my annual physical, I get tested for all the main STDs: HIV, syphilis, chlamydia, and gonorrhea, just for my own peace of mind. I always test clean, however every so often I experience discharge after urination. If I'm disease free, what could cause this? I've also experienced an occasional discomfort like a mild burning during urination, but it's nothing severe or constant. Any thoughts?

ANSWER
What you describe could be an STD called urethritis. About 40% of cases are caused by bacteria like chlamydia or gonorrhea. Other cases may be caused by other bacteria like mycoplasma, viruses like herpes or even yeast. Receiving oral sex can cause urethritis from bacteria in the mouth. Other causes can include reactions to chemicals or lubricants like N-9. Rarely urinary tract infections and kidney stones can cause urethritis. Only a doctor can make a diagnosis after an examination. For more information on non-gonoccochal urethritis (NGU), click here.

To your health,
Dr. K