Use the injection exactly as directed by your doctor. Do not use more of it and do not use it more often than ordered. If too much is used, the erection may become so strong that it lasts too long and does not reverse when it should. This condition is called priapism, and it can be very dangerous. If the effect is not reversed, the blood supply to the penis may be cut off and permanent damage may occur.
Contact your doctor immediately if the erection lasts for longer than 4 hours or if it becomes painful. This may be a sign of priapism and must be treated right away to prevent permanent damage.
If you notice bleeding at the site when you inject the medicine, put pressure on the spot until the bleeding stops. If it doesn't stop, check with your doctor.
It is important for you to examine your penis regularly. Check with your doctor if you find a lump where the medicine has been injected or if you notice that your penis is becoming curved. These may be signs that unwanted tissue is growing (called fibrosis), which should be seen by your doctor.