Can i contact hiv with one time sex?

YES: The risk of contracting from an infected partner depends on a number of factors, including type of sex, anal, vaginal, or oral (in decreasing order of risk, but all carry risk). Transmission can occur with one exposure, and there are biological factors that increase risk (other STDs, viral load, and inflammation, just to name a few). Condoms are not 100%, but they are highly effective. Take care