Taking birth control pills for several consecutive months to brown matter may be missed or drug side effects caused by. 1. Missed dose of drugs: taking short-acting contraceptives is a common contraceptive measure for women, need to be taken regularly under the guidance of a doctor, before taking the drug to exclude cardiovascular disease, thrombotic diseases and other contraindications. When the medication is not taken, it can cause irregular vaginal bleeding, which can be manifested as brown vaginal discharge for several months in a row, and generally do not need to be dealt with, with the prolongation of the medication time will gradually stop. 2. drug side effects: because the contraceptive pill for hormonal drugs, after taking due to the influence of exogenous hormones, may affect the endometrium irregular shedding, which is manifested in a few consecutive months of vaginal flow of brown secretion, usually will be gradually returned to normal after stopping the drug, usually do not need special treatment. Taking birth control pills for several consecutive months to brown discharge when you can go to the hospital, can be given under the guidance of the doctor to deal with.