QUESTION
After oral sex I always use mouthwash as soon as possible. After someone has masturbated on my chest or someone has performed oral sex on me, I try to take a shower with lots of antibacterial soap. Sometimes I even put rubbing alcohol on areas I know were touched by semen. Is this ridiculous?

ANSWER
While washing your hands and genital area thoroughly before and after oral-anal sex (rimming) reduces transmission of STDs like shigella and parasites like amoeba, etc., there are no data that the same actions do anything after sexual activities which involve semen. In particular, mouthwash after performing oral sex won't do much except make your breath smell sweeter.

Based on the activities your mentioned, your overall risk of contracting an STD, including HIV, is very low. There is no health reason to rush off to the bathroom after your pleasure. If it makes you feel better emotionally, though, there doesn't seem to be any harm. You may want to switch from an antibacterial soap to a regular one (most regular soaps are indeed antibacterial) as evidence has shown regular soap and water to be as effective as these antibacterial soaps for cleanliness and hygiene.

To your health,
Dr. K