What are the common side effects of alpha‑adrenergic blockers used to treat benign prostatic hyperplasia?

Alpha-Blocker Side Effects in Benign Prostatic Hyperplasia

The primary adverse events associated with alpha-blockers used for BPH are orthostatic hypotension, dizziness, asthenia (tiredness), ejaculatory dysfunction, and nasal congestion, with the specific side effect profile varying by agent. 1

Common Side Effects Across All Alpha-Blockers

The following adverse events occur with alpha-blocker therapy for BPH:

• Orthostatic hypotension – blood pressure drops upon standing, particularly with doxazosin and terazosin 1, 2
• Dizziness – related to cardiovascular effects and blood pressure changes 1, 3
• Asthenia (tiredness/fatigue) – a common complaint that may limit tolerability 1, 4
• Nasal congestion – due to alpha-receptor blockade in nasal vasculature 1, 4
• Ejaculatory dysfunction – including retrograde ejaculation or reduced ejaculate volume 1

Agent-Specific Side Effect Profiles

Tamsulosin

• Lower probability of orthostatic hypotension compared to non-selective agents like doxazosin and terazosin 1, 4
• Higher probability of ejaculatory dysfunction compared to other alpha-blockers 1, 4
• Minimal blood pressure reductions in normotensive patients, making it safer in those without hypertension 5

Silodosin

• Highest rate of abnormal ejaculation among all alpha-blockers, reported as the most common adverse effect 6
• Very low incidence of orthostatic hypotension due to true α1A-receptor selectivity 6
• Favorable cardiovascular safety profile compared to older agents 6

Doxazosin and Terazosin

• Significant cardiovascular side effects including postural hypotension, asthenia, and dizziness 5
• Require dose titration to minimize orthostatic effects 1, 6
• In men with hypertension and cardiac risk factors, doxazosin monotherapy was associated with higher incidence of congestive heart failure compared to other antihypertensive agents 1

Alfuzosin

• Potentially lower risk of orthostatic hypotension compared to doxazosin/terazosin 1
• Does not require dose titration 6
• Clinically "uroselective" despite lacking receptor subtype selectivity 3

Critical Clinical Considerations

Intraoperative Floppy Iris Syndrome (IFIS)

• All alpha-blockers, particularly tamsulosin, are associated with IFIS during cataract surgery 4
• Patients planning cataract surgery should delay alpha-blocker initiation until after the procedure 4
• Ophthalmologists must be informed if patients are taking alpha-blockers 4

Blood Pressure Interactions

• Alpha-blockers should not be assumed to constitute optimal management of concomitant hypertension 1
• Patients with hypertension may require separate management of their blood pressure with other agents 1
• The introduction of doxazosin or terazosin may temporarily affect blood pressure control in patients already on antihypertensive therapy 5

Cardiovascular Contraindications

• Alpha-blockers are contraindicated in patients with cardiac failure, renal failure, prior cerebrovascular incidents, and tendency to hypotension 7

Practical Management Algorithm

For patients concerned about orthostatic hypotension or on multiple antihypertensives:

• Choose tamsulosin, alfuzosin, or silodosin (no dose titration required) 6

For patients concerned about sexual side effects:

• Avoid silodosin (highest ejaculatory dysfunction rate) 6
• Consider alfuzosin or doxazosin/terazosin (lower ejaculatory dysfunction) 1

For normotensive patients:

• Tamsulosin produces minimal blood pressure changes (only 6.7% experienced systolic BP <90 mmHg or diastolic <60 mmHg, not significantly different from placebo at 5%) 4

For patients planning cataract surgery:

• Defer all alpha-blocker therapy until after surgery 4