It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly and for any problems that may be caused by this medicine.
Do not use this medicine if you are taking certain medicines such as ketoconazole (Nizoral®), itraconazole (Sporanox®), or ritonavir (Norvir®).
Dizziness, lightheadedness, or fainting may occur after you take this medicine, especially when you get up from a lying or sitting position. Getting up slowly may help lessen this problem. If you feel dizzy, lie down so you do not faint. Then sit for a few moments before standing to prevent the dizziness from returning.
This medicine may cause some people to become dizzy or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert.
You should seek medical attention right away if you experience a prolonged erection. This is an extremely rare side effect, but if it goes untreated, can result in permanent erectile dysfunction (impotence).
Stop using this medicine and check with your doctor right away if you have arm, back or jaw pain; chest pain or discomfort; chest tightness or heaviness; fast or irregular heartbeat; nausea; shortness of breath; or sweating.
This medicine may affect the results of the prostate specific antigen (PSA) test, which may be used to detect prostate cancer. Make sure you tell all of your doctors that you are using this medicine.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.