USES: Doxazosin is used alone or in combination with other drugs to treat hypertension (high blood pressure). It works by relaxing blood vessels so blood can flow more easily. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems.SES: Doxazosin is used alone or in combination with other drugs to treat hypertension (high blood pressure). It works by relaxing blood vessels so blood can flow more easily. Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems.