EllaOne is a brand name for a drug that contains ulipristal acetate as an active component. It is a sort of emergency contraception, popularly known as the "morning-after pill," that can be used to prevent pregnancy for up to 120 hours (5 days) following unprotected sexual intercourse or contraceptive failure. EllaOne works by blocking or postponing ovulation, or the release of an egg from the ovary. It does not end a pregnancy and should not be used as a regular means of contraception. EllaOne may cause headaches, nausea, stomach discomfort, menstruation irregularities, and dizziness. Those who are allergic to any of its constituents or who have serious liver issues should avoid using it.

Further information about the medication visit the link:

https://www.nhs.uk/conditions/contraception/emergency-contraception/