Prescription medication prices can increase for a few reasons. Often, it costs the manufacturer more to make the medication, so you end up paying more at the pharmacy. Sometimes, if there's a shortage of a popular medication due to high demand or not enough supply, the price may also increase.Prescription medication prices can increase for a few reasons. Often, it costs the manufacturer more to make the medication, so you end up paying more at the pharmacy. Sometimes, if there's a shortage of a popular medication due to high demand or not enough supply, the price may also increase.