Black Line Edge Imagen titulada Use a Condom Step 13 13 Replace the condom if you practice different types of sex. If you are going to have vaginal sex after having anal sex, change your condom to reduce the risk of infection. For example, the E. coli bacteria in the rectum can cause a bladder infection or a severe vaginal infection. If you practice oral sex after anal, a serious stomach infection can occur. You should also replace the condom if you use it on a sex toy that you share with your partner. Basically, if the condom has your fluids, you should change it before sharing it.