OBJECTIVES: A daily assessment of the speed of action and effectiveness of treatment of a combination of paracetamol and codeine in patients suffering from intense pain, which has progressed since less than 7 days. METHODS: A multicentre longitudinal observational prospective study carried out in metropolitan France using data collected by general practitioners who agreed to participate. RESULTS: A total of 574 patients treated by a paracetamol-codeine combination (600mg/50mg and 400mg/20mg) were included. The severity of pain measured at inclusion using a visual numeric scale was 7±1.28. The severity of pain measured after half a day of treatment was 5.61±1.87 and 5.28 ± 1.86 at the end of the first 24 hours of treatment. A significant improvement in pain was observed from the first half-day (p<0.001). The severity of pain on the 2nd, 4th and 7th evenings was respectively 4.08±1.85; 2.76±1.76 and 1.79 ±1.69 On D1, 69.7% declared treatment to be effective, 61.04% were satisfied with their treatment and 79.26% did not observe any side effects to the treatment. On D7, 96.15%  (D3, 91.3% ) declared treatment to be effective, 87.10% were satisfied with their treatment and 88.96% did not observe any side effects to the treatment. 8 out of 10 patients did not complain about side effects related to the treatment. CONCLUSIONS: A reduction in pain within the first 12 hours showed the pertinence of treatment using a paracetamol-codeine combination. This pertinence was confirmed by two-thirds patients who declared the treatment to be effective from the 1st day, and 91% of them declared this on the 3rd day