if ur only concern is pregnancy.. then u can either use morning after pill (if its a one off thing.. dont take it too often if u're having consistently), birth control pill (1 month cycle) or birth control injection (3 months).

condoms are more important to prevent HIV and STDs. its not 100% safe, only bout 98% save, but hey.. at leas there's a precaution rite? if u still get it.. then i guess that's just luck. after all, who ask u to be itchy?