and i'm glad you asked. i think maybe your friend misunderstood what the doctor told her. chlamydia is a very common sexually transmitted infection (sti). you can get chlamydia through vaginal anal or possibly even oral sex. switching from anal sex to vaginal sex in one session may not make you more likely to get chlamydia. however anyone who does have anal sex without a condom before vaginal sex should make sure her partner has thoroughly cleaned his penis. otherwise you could transfer intestinal bacteria (or other types of stis) into the vagina which might not be good. obviously your best bet is always to practice safe sex by having your partner use a condom. it's not perfect because it won't necessarily protect you (or him) from stds like human papillomavirus (hpv) or herpes but it's better than no protection at all. hope this helps!
can you get chlamydia just from switching from anal sex to vaginal sex? . i have a friend who had been previously tested for any stds and was negative then after she had sex with one guy (during sex she had anal sex and then went back to vaginal sex) she had chlamydia. her doctor said that the switching from anal to vaginal could possibly give her the chlamydia. is that true? i have also been told that you can contract all sorts of things from switching and just wanted to do my own research.