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 multi-centre longitudinal observational prospective study carried out in metropolitan France using data collected by general practitioners who agreed to participate.RESULTS:   A total of 804 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 ± 1.3. The severity of pain measured after half a day of treatment was 5.29 ± 1.87 and 5.65 ± 1.85 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 4.09 ± 1.87; 2.74 ± 1.8 and 1.78 ± 1.7. On D1, 70.8% declared treatment to be effective, 62.56% were satisfied with their treatment and 80.5% did not observe any side effects to the treatment.  On D3, 91.5% declared treatment to be effective, 82.4% were satisfied with their treatment and 83.12% did not observe any side effects to the treatment.  On D7, 95.9% declared treatment to be effective, 87.2% were satisfied with their treatment and 89.2% did not observe any side effects to the treatment. 9 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 2/3 patients who declared the treatment to be effective from the 1st day, and 91% of them declared this on the 3rd day