Background: The rational use of medicine is fundamental to ensure effective and safe patient medicine treatment, and hence, should be monitored. Undisputable evidence exists for the teratogenic risk factors associated with sodium valproate. Consequently, the Western Cape Department of Health introduced a policy (2019) recommending alternatives for valproate in women of childbearing age, including lamotrigine or levetiracetam as alternatives for patients on antiretrovirals. This study aimed to describe the change in the consumption of valproate, lamotrigine and levetiracetam after a policy implementation in public sector health facilities of the Western Cape, South Africa.Methods: This observational study followed a quasi-experimental design. Consumption data from the Cape Medical Depot over the period 01 April 2018 to 31 March 2020 were analysed retrospectively. Consumption was presented as a defined daily dose (DDD) per 1000 population per quarter for sodium valproate, levetiracetam and lamotrigine for the Western Cape province, urban and rural areas. Consumption 12 months before was compared with consumption 12 months after policy implementation.Results: Post-policy implementation, valproate consumption remained unchanged provincially (3.3%; p = 0.255), in urban (7.8%; p = 0.255) and rural (1.5%; p = 0.701) areas. Lamotrigine consumption increased significantly provincially (30.7%; p = 0.020) and in urban areas (54.5%; p = 0.002); however, rural (26.1%; p = 0.108) areas did not show significant change. Provincially, valproate consumption remained substantially higher (209 DDDs/1000 population per quarter) compared with lamotrigine consumption (32.22 DDDs/1000 population per quarter).Conclusion: In the Western Cape public sector, the consumption of sodium valproate remained unchanged 12 months after policy implementation. Although there were significant increases in lamotrigine and levetiracetam consumption, the consumption was considerably less compared with sodium valproate consumption.