Re: Zoloft, you can expect, on average, that 1%-2% of the active ingredient will be secreted in breast milk. There is no evidence thus far that infants incur damage from such exposure, but due to lack of certainty there is a risk. I am not aware of studies which reveal if methylphenidate (Ritalin) is secreted in breast milk. To be entirely safe, it is best not to nurse while taking the medications you are prescribed. If you must take the medicines, it is best to stop breast feeding. If you must take the Ritalin, take your dose immediately after you have fed your child, or just at the point your child is beginning his long nap.