Unwanted 72 is an emergency contraception tablet, rather than a birth control pill. It’s only suitable if you’ve put yourself at risk of getting pregnant by having unprotected sex, or because of contraceptive failure.
Unwanted 72 should be taken within 72 hours of having had unprotected sex, or having experienced contraceptive failure. Unwanted 21 is effective only if it’s taken regularly without missing any doses.