I've beenbeen on birth control for 1.5 months. if i have unprotected sex should i take plan b?

If you mean you have: Been OFF birth control, then you should get a reliable method of contraception. If you had intercourse within the last 2 days and you are off birth control, then get plan B ASAP. If you have been ON birth control for 1.5 months, you are protected from pregnancy. You do not need a backup method to prevent pregnancy. BUT you are not protected from sexually transmitted infection.Condoms are best4this