A nurse is teaching a client about potential adverse effects of oral contraceptives. For which of the following adverse effects should the nurse instruct the client to notify the provider immediately?

A. Nausea is a common and generally mild side effect of oral contraceptives and does not typically require immediate medical attention. B. Persistent headaches may indicate an increased risk of stroke or hypertension, especially in clients with other risk factors. This could be a sign of a serious adverse effect and should be reported to the provider immediately. C. Breast tenderness is a common and usually benign side effect of hormonal contraceptives. D. Abdominal bloating may occur but is not typically dangerous or an urgent concern.