Retinoic acid causes malformations of the fetus, but should be no problem for the nursing infant. I don't know what Psorcon is, we don't have it under that brand name in Canada. Calcipotriol (Dovonex) is essentially vitamin D. Only about 5% of the total amount the mother applies will be absorbed. The concentration of any of these medications in the blood, and therefore the milk, is so low as to be of no consequence. By the way, the mother can stop giving vitamins to the baby, retinoic acid being, essentially, vitamin A, and the other D (which the baby doesn't need anyhow, but many physicians say they do). Maybe Psorcon is vitamin C (the old tri-visol, eh?) As usual, when in doubt, assume that breastfeeding is of so little importance to the mother and baby that it can be stopped on the *suspicion* that the drug is not okay. AAARGH! Jack Newman, MD, FRCPC