It is important that your doctor check your progress at regular visits to make sure that this medicine is working properly. This is especially important for elderly patients, who may be more sensitive to the effects of this medicine.
For patients taking this medicine for high blood pressure :
Do not take other medicines unless they have been discussed with your doctor. This especially includes over-the-counter (nonprescription) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, since they may tend to increase your blood pressure.
Dizziness, lightheadedness, or sudden fainting may occur after you take this medicine, especially when you get up from a lying or sitting position. These effects are more likely to occur when you take the first dose of this medicine. Taking the first dose at bedtime may prevent problems. However, be especially careful if you need to get up during the night. These effects may also occur with any doses you take after the first dose. Getting up slowly may help lessen this problem. If you feel dizzy, lie down so that you do not faint. Then sit for a few moments before standing to prevent the dizziness from returning.
The dizziness, lightheadedness, or sudden fainting is more likely to occur if you drink alcohol, stand for a long time, exercise, or if the weather is hot. While you are taking this medicine, be careful to limit the amount of alcohol you drink. Also, use extra care during exercise or hot weather or if you must stand for a long time.
Doxazosin may cause some people to become drowsy 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, drowsy, or are not alert. After you have taken several doses of this medicine, these effects should lessen.
The possibility of priapism, a painful or prolonged erection of the penis, is a rare side effect that can occur when taking doxazosin and must have immediate medical attention.