This study investigates the treatment of acute pain, an unpleasant feeling caused by an injury. The overall purpose of the study is to gain more information that the pain relief medicine Penthrox(Methoxyflurane) administered using the Penthrox Inhaler(a distinctive green, whistle like object that you breathe through) is safe and works at relieving pain in patients aged 12 years and older who are admitted to a hospital Emergency Department with a minor injury (known as trauma).

Inclusion Criteria:

• Patients 12 years of age or older who are able to give written informed consent or who are accompanied by a parent(s)/legal guardian able to provide written informed consent on their behalf.
• Evidence of signed and dated informed consent document(s) indicating that the patient (and/or a parent/legal guardian) has been informed of all pertinent aspects of the study.
• Pain Score ≥ 4 to ≤ 7 as measured using Numerical Rating Scale (NRS) at the time of admission, due to minor trauma.

Exclusion Criteria:

• Life-threatening condition requiring immediate admission in the Operating Room or Intensive Care Unit.
• Presence of any other clinical condition(s) that may, in the opinion of the investigator, impact on the patient's ability to participate in the study, or on the study results, including history of head injury and/or altered consciousness.
• Unable to provide written informed consent.
• Known pregnancy or lactation
• Acute intoxication with drugs or alcohol, based on the judgement of the attending physician.
• Treatment with any analgesic agent within 5 hours prior to presentation to ED (except diclofenac sodium which is prohibited within 8 hours prior to presentation to ED).
• Current ongoing use of analgesics for chronic pain.
• Use of an investigational product within one month prior to presentation to ED.
• Known personal or familial hypersensitivity to fluorinated anaesthetics.
• Known personal or familial history of malignant hyperthermia.
• Clinically significant respiratory depression.
• Use of methoxyflurane in the previous 4 weeks.
• Known pre-existing clinically significant renal or hepatic impairment according to the judgement of the clinician.
• Clinically significant cardiovascular instability.