No-one wants one night to have a lasting effect on their life. Left untreated certain STIs like Chlamydia and Gonorrhea, can lead to long term health consequences like Infertility. Make sure you get checked regularly, and remember that condoms are the only form of contraception that protects against pregnancy and STIs. Read more information about the long term consequences of STIs.
No method of contraception can give you 100% protection against pregnancy, HIV or sexually transmitted diseases.