Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Blood cell counts: This medication may cause leukopenia (low white blood cell count), which can mean your immune system is weak. If you develop a fever, talk to your doctor as soon as possible. Your doctor will also perform blood tests regularly to monitor your blood cell counts.
BPH: Doxazosin therapy does not cure or change the natural course of benign prostatic hyperplasia (BPH or enlarged prostate). It does not slow down or stop the progression of BPH. Note that BPH is not the same thing as prostate cancer, although they do cause many of the same symptoms. It is possible for men to have both BPH and prostate cancer at the same time.
Your doctor may check for prostate cancer before starting doxazosin and once a year after you turn 50 years old (40 years old if you have a family member who has had prostate cancer).
Drowsiness/reduced alertness: Due to the possibility of excessive lowering of blood pressure, people taking doxazosin should avoid driving or performing hazardous tasks for 24 hours after the first dose, after the dose is increased, and when the medication is started again after not taking it for a period of time. They should also avoid situations where injury could result from loss of consciousness.
Liver and kidney: If you have reduced liver function, are taking medications that reduce liver metabolism, or have reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Low blood pressure: The first or first few doses of doxazosin can cause a marked lowering of blood pressure, especially when moving from a sitting or lying position to a standing position, and may even result in a loss of consciousness. A similar effect can occur if therapy is started again after stopping for more than a few doses. These effects are most likely to occur 2 to 6 hours after taking the medication.
While loss of consciousness due to excessive blood pressure lowering is the most severe side effect of doxazosin, other symptoms of low blood pressure such as dizziness, lightheadedness, or loss of sense of balance can occur.
Lie down when symptoms of low blood pressure occur and be careful when getting up from a lying position (move slowly). If dizziness, lightheadedness, or palpitations are bothersome, report them to your doctor so that dose adjustment can be considered.
The likelihood of excessive lowering of blood pressure can be reduced by the doctor limiting the initial dose of doxazosin to 1 mg, by increasing the dosage slowly, and by starting any other blood pressure medication as directed by your doctor.
Long-term use: Long-term safety and efficacy (i.e., for more than 4 years) have not yet been established for the use of doxazosin in the treatment of BPH.
PDE-5 inhibitors: If you are taking a PDE-5 inhibitor (e.g., sildenafil, tadalafil, or vardenafil) while taking this medication, you may be at risk for low blood pressure. Talk to your doctor.
Pregnancy: There are no studies on the effect of using this medication during pregnancy. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: It is not known if this medication passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding. In general, women should not breast-feed while taking this medication.
Children: The safety and effectiveness of using this medication have not been established for children. It is not recommended for use by children.
Seniors: Seniors may experience excessive lowering of blood pressure or dizziness when they take doxazosin. Talk to your doctor if you have any concerns.