It is not common for Flomax to cause an increase in blood pressure. High blood pressure can be caused by various factors such as certain over-the-counter medications, natural health products, forgetting to take anti-hypertensive medication, smoking, or stress. It can also be caused by kidney stones. It is recommended to consult a doctor to investigate further. In the meantime, it is advised to monitor blood pressure multiple times a day and keep a record. Other measures to control blood pressure include maintaining a healthy diet, reducing salt intake, maintaining a healthy weight, limiting alcohol consumption, quitting smoking, and regular physical activity.