Oral contraceptives have long been known to be affected by the consumption of other drugs. Especially, the drugs that have an effect on the liver are known to hinder the normal functioning of the oral contraceptives.

 It is observed that drugs for TB, some antibiotics and some drugs to resist fungal infections cause higher pregnancies as compared to when these drugs are not consumed. That is the reason why some of the doctors while prescribing antibiotics advice to take extra contraceptive pills. These drugs speed up the functioning of the liver and result in a fast metabolism.

This mars the effect of the contraceptive pills. Even the diet pills are known to have a bad effect on birth although this has not been established fool proof, but studies are going on. Even the claim that antibiotics come in way of normal functioning of the birth control pills is dicey and people vary in their opinions. Some studies even suggest that diseases reduce the effectiveness of the birth control pills. These diseases are diarrhea, gastritis and flu. While infected with these diseases, the pills are not absorbed to the fullest. But this is not an established fact.