From the Guidelines
Orthostatic hypotension caused by 8 mg doxazosin often improves over time as the body develops tolerance to this side effect, typically within 2-4 weeks of starting treatment. However, complete resolution varies between individuals, with some patients continuing to experience some degree of orthostatic symptoms even with continued use. According to the American Urological Association (AUA) guideline on management of benign prostatic hyperplasia 1, alpha-blocker therapy, including doxazosin, can cause orthostatic hypotension, dizziness, tiredness, ejaculatory problems, and nasal congestion as primary adverse events.
To manage this side effect, several strategies can be employed:
- Start with a lower dose (1-2 mg) and gradually increase to 8 mg over several weeks
- Take doxazosin at bedtime to minimize daytime symptoms
- Stay well-hydrated
- Avoid alcohol
- Rise slowly from sitting or lying positions
- Consider compression stockings if symptoms are severe
If orthostatic hypotension remains problematic after 4-6 weeks at a stable dose, it is essential to discuss with your healthcare provider about possible dose adjustment or alternative medications, as the AUA guideline suggests that large, well-designed, direct comparator trials are needed to substantiate claims of superior safety 1. Doxazosin causes orthostatic hypotension by blocking alpha-1 receptors in blood vessels, preventing norepinephrine from causing vasoconstriction, which normally helps maintain blood pressure when changing positions. The body gradually compensates for this effect through other blood pressure regulatory mechanisms, explaining why symptoms often improve with continued use.
From the FDA Drug Label
Postural hypotension with or without symptoms (e.g., dizziness) may develop within a few hours following administration of doxazosin. However, infrequently, symptomatic postural hypotension has also been reported later than a few hours after dosing. The FDA drug label does not answer the question.
From the Research
Orthostatic Hypotension Caused by Doxazosin
- Orthostatic hypotension, also known as postural hypotension, is a side effect of doxazosin, an alpha blocker used to treat hypertension and benign prostatic hyperplasia 2, 3, 4, 5.
- The studies suggest that doxazosin can cause a significant reduction in standing systolic and diastolic blood pressure, which can lead to orthostatic hypotension 2, 4.
- However, the studies also indicate that the incidence of orthostatic hypotension may decrease over time as the body adapts to the medication 3, 4.
- One study found that doxazosin decreased blood pressure in patients with essential hypertension without an excessive decrease in standing blood pressure, suggesting that the risk of orthostatic hypotension may be mitigated with continued use 4.
Resolution of Orthostatic Hypotension Over Time
- The studies suggest that the side effects of doxazosin, including orthostatic hypotension, may resolve or decrease in severity over time as the body adapts to the medication 3, 4.
- One study found that most side effects, including dizziness and vertigo, were mild or moderate and disappeared or were tolerated with continued therapy 3.
- Another study found that doxazosin decreased blood pressure in patients with essential hypertension without an excessive decrease in standing blood pressure, suggesting that the risk of orthostatic hypotension may be mitigated with continued use 4.