Small, occasional doses of dexchlorpheniramine would not be expected to cause any adverse effects in breastfed infants. Larger doses or more prolonged use might cause effects in the infant or decrease the milk supply, particularly in combination with a sympathomimetic such as pseudoephedrine or before lactation is well established. Single bedtime doses after the last feeding of the day may be adequate for many women and will minimize any effects of the drug. The nonsedating antihistamines are preferred alternatives.