Methods and compositions for treating pain are disclosed. The compositions are based on dry powders comprising microparticles of diketopiperazines and an analgesic active agent. The analgesic in the compositions comprises one or more peptide analgesics or derivatives thereof, which are administered to a subject using a pulmonary inhalation drug delivery system comprising a dry powder inhaler and the analgesic composition. The present compositions produce fewer side effects associated with current opioid therapy.