This is very personal and embarrassing but if i had sex with someone a few hours before i was sent to the lab for a drug test and he came in me a few hours before, is it possible i will faily drug test?

Sperm should not affect the outcome of a urine drug screen, although I read one report of a female who did test positive for cocaine from her partners sperm. From my reading the predominant opinion is that sperm in the vagina shouldn't contaminate a urine drug screen. To be sure, submit your urine using the clean catch technique keeping vaginal contents away from the urine stream.

Agree with Dr. Colantino. What you described has a very remote risk of resulting in a positive urine drug test. The remote circumstance would be your partner being a heavy drug user and the semen contaminating your urine. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol or weed.