Acute pain relief in emergency setting is still a public health priority. Pain is the primary reason for emergency room use, but the situation of "oligo-analgesia" persists in all countries. Intravenous morphine titration has become the standard method for severe acute pain management in the emergency department, but it is still insufficiently implemented. Deviations from the recommended protocol are common: initial additional loading doses, unusually extended intervals between bolus, premature discontinuation. Several factors contribute to these difficulties: heaviness of its setting up, especially in overcrowding case, procedure rigidity, high consumption of nursing time. This method requires a systematic intravenously route, which has several inconvenients: algogenic procedures, coupled initial diagnostic venous sampling (delay for analgesia), excessive "medicalization" of ambulatory patients (risk of infection and less mobility in the emergency department). An alternative to reduce the analgesic latency in emergency department, without losing the benefits of tolerance and safety should be welcome. The inhaled route looks promising, but has yet not been enough evaluated in adults, and even less in the emergency room. Aerosol techniques change from one study to another (molecules, materials, doses, painful intensities included, judgment criteria and assessment times). A morphine titration by aerosol therapy could be an interesting alternative to the standard method disadvantages, using faster, painless and easier procedures, leading to "demedicalization".