<prompt> Minimum effective dose of ethinyl estradiol in combination oral pills is:10 mg35 mg50 mg75 mg  <response>: Ans. is a, i.e. 10mgRef: Dutta Obs. 6thed, p542; Shaw 15thed, p231Intensive pharmacological research clinical trials conducted to minimise the adverse effects of estrogen without reducing the contraceptive efficacy, resulted in lowering the dose of oestrogen to a minimum of 20mg or even 15mgThus, Remember: Low dose OCPs have estrogen less than 50mcg 30-35mcg usually - Ref: Dutta Obs 6thed, p542 Very low dose OCPs have estrogen 20mcg Minimum effective dose of Estrogen 10mcg 