General contraceptive pills do not need to avoid the mouth, but if you just ate the pill immediately spit out, it is useless. So it is best to take the pill two hours before and after fasting, or do not want to fast, you can take it before bedtime is no problem, the main purpose is to let the drug fully absorbed, do not spit out, no effect, spit out also have to take another piece, this is also not good. So it is best to take the pill on an empty stomach two hours before and after taking it, and then take the pill orally, which may be more effective. Also note that some drugs have synergistic effects, such as rifampicin, phenytoin sodium, carbamazepine and other drugs, can not be eaten together with the contraceptive pill. Because they are consumed together often occur drug interactions. So when taking drugs, it is best to read the instructions there is no interaction of drugs, or when taking certain drugs are not sure, look at the instructions or go to the hospital and ask the doctor, so relatively safe, do not swallow several drugs together with their mouth, which can produce drug interactions or adverse reactions.