Minoxidil is a vasodilator, so it can lower blood pressure and cause lightheadedness, a faster heart rate, or fluid retention in the ankles and feet. These effects are dose-related and far less common at hair-loss doses than at the doses used for hypertension, but they are the reason this is a prescription medication requiring clinician oversight. Tell your clinician about any heart condition and every blood-pressure medication you take, and report chest pain, shortness of breath, swelling, or sudden weight gain right away. See the full Important Safety Information for this product.