The invention relates to a device for weaning an infant from receiving liquids from a baby bottle, the device comprising a flanged pacifier (1), the interior space thereof being adapted to accommodate small amounts of an agent to be dosed to the infant, the agent having a sweet-tasting but not caries-promoting nature to the infant's teeth and further being soluble in the infant's own saliva, the structure of the pacifier (1) having a perforated nipple portion (6) for inflow and outflow of the infant's saliva, a body part (2, 10) surrounding the base of the pacifier (1) and, cooperating with the latter part, a closing cap (3) adapted to seal the central opening of the wide-diameter base of the pacifier (1). The invention is characterized in that the closing cap includes a rim (3a) and a closed-bottom plug portion (5) that in the closed position of the closing cap extends into the void interior of the base (4) of the pacifier so as to occupy a major volume in pacifier interior space and, simultaneously, to prevent the dosed agent from escaping from the interior space of the nipple portion (6) of the pacifier toward the base (4) of the pacifier.