How soon after quitting diet pills can i try to get pregnant?

, see below: We saw no evidence that Phentermine can cause any birth defects but in your situation (starting a pregnancy) you should talk this over with your doctor first. A few women take it while pregnant but only under a doctor's care and then only when it is clearly needed. Phentermine is in Pregnancy Category C. Whatever testing has been done on drugs in this category in animals has uncovered a chance of harm. However, the likelihood is considered small enough to justify taking the drug if it's essential to your health. A general "rule of thumb" is that it takes five and a half "half-lives" for the body to eliminate a drug to the point where it has no effect.