Breastfeeding and Medication You can breastfeed even when taking most medicines, but always check with your doctor or breastfeeding consultant first. Some drugs pass into breast milk and a few can be harmful to your baby. Some medications can also change how much milk you make. For instance, birth control pills with both estrogen and progestin can limit milk production, while other types actually improve milk supply. Your doctor can help you find a medication that is okay to take while breastfeeding. You should wait at least 6 weeks after delivering to start birth control pills (progestin only), birth control patches, take Depo Provera injections, or use cervical rings. This will allow time to establish your milk supply. Some women find that their milk decreases after starting birth control. Work with your doctor or family planning clinic to find a method that works best for you. Prenatal vitamins are fine while breastfeeding. Always talk with your doctor before taking other vitamins, herbal remedies or “dietary supplements.” These products may contain chemicals that could reduce your milk supply or harm your baby.