Background: Drug therapy can improve a patient’s quality of life and health outcomes if only used properly. However, data on prescription quality at primary health care facilities in Tanzania is scanty. The objective of this study was to assess the quality of drug prescriptions in selected health care facilities in two districts of Mwanza, Tanzania.

Methods: This descriptive cross-sectional study was carried out in Ilemela and Nyamagana districts in Mwanza, Tanzania. The study included 20 randomly selected public and private health care facilities. A random sample of the patient records in each facility was included. From each patient record, the latest prescription was assessed. Information assessed and recorded included prescribing indicators, frequency of prescription error, various formulations and groups of drugs prescribed. Prescribers were interviewed on factors affecting prescribing practices.

Results: A total of 570 prescriptions were studied. The average number of drugs prescribed per encounter was 2.8. The percentage of encounters with an antibacterial agent prescribed was 33.8% and injections constituted 7.9% of cases. Prescriptions by generic name were 85.8% while 90.6% of drugs prescribed were from the national essential drug list. Antibacterial agents, analgesics and antimalarial agents accounted for 75.3% of all drugs prescribed. Of all prescriptions, 485 (85.1%) had at least an error. A total of 1,177 errors were made. Errors of omissions accounted for the majority (99.3%) of all errors. The most commonly observed missing prescription particulars were the drug strength (23.2%) and patient weight (22.2%). The average number of drugs per encounter was higher in private facilities (3.2) than in public facilities (2.4) ( P <0.0001). The range of drugs per prescription was also higher in private (1-7) than in public facilities (1-5) ( P <0.0001). There were statistically significant differences in the distribution of various drug groups prescribed between public and private facilities and between health centres and dispensaries ( P <0.001 and 0.027, respectively).

Conclusion: Prescribing of higher number of drugs than the WHO recommendations and overuse of antibiotics is still a problem at health care facilities in Mwanza Tanzania. The frequency of occurrence of prescription errors found during the study was considerably high.