The incidence of side effects of short-acting contraceptives varies from person to person, including nausea (generally lasting less than 24 hours), vomiting, dizziness and other early pregnancy reactions, because progesterone components in drugs are playing a role. There may also be irregular uterine bleeding. Some women will have vaginal drip bleeding after taking medicine, and generally do not need treatment. After taking 1-3 months, the symptoms usually disappear.