What Medicine Do I Need To Buy Over The Counter To Have My Period?

I will not recommend any OTC or prescription medicine to induce periods. Because you have not mentioned your age in question. All medicines can cause many side effects. Proper diagnosis of underlying cause of absence of periods should be investigated. This can be done by the doctor.  To get treatment, first of all get pregnancy test if you are a sexually active woman. Then visit a doctor for diagnosis and treatment who may prescribe some hormonal treatment. Usually, birth control pills can induce periods in those ladies who were previously having periods.