The study is prospective, double blinded, randomised controlled and has the purpose to compare the analgesic effects of ketorolac or morphine intravenous in low back pain.

The study will take place in the Emergency Department of the Clinical Emergency Hospital Bucharest and will compare the analgesic effects of ketorolac tromethamine against morphine in low back pain.

The patients will be randomised to receive either ketorolac 30 mg intravenous (diluted in 20 ml of 0,9% saline) or morphine 0,1 mg/kg weight intravenous. A scale of 1-10 will be used for measuring the pain, and the effects of the treatment will be evaluated at 15 minutes and 30 minutes from the administration of the drugs. After 30 minutes if there is no significant reduction of the pain a rescue therapy will be used : acetaminophen 1 g, sodic metamizole 1g both diluted in 500 ml saline and the other medication not used from the study (morphine or ketorolac tromethamine).

Inclusion Criteria:

• clinical diagnosis of musculoskeletal low back pain
• grade 5 pain on a 1-10 visual pain scale

Exclusion Criteria:

• contraindications of ketorolac or opioids
• pregnancy
• known allergies to ketorolac or opioids
• post-traumatic low back pain
• refusal of participation