What is prazosin used for?

Uses of Prazosin in Clinical Practice

Prazosin is primarily FDA-approved for the treatment of hypertension, but it is also widely used off-label for PTSD-associated nightmares, with substantial evidence supporting this application. 1, 2

Primary FDA-Approved Indication

• Prazosin is officially indicated for the treatment of hypertension, working as an alpha-1 adrenergic receptor antagonist to lower blood pressure and reduce the risk of fatal and nonfatal cardiovascular events 1
• It can be used alone or in combination with other antihypertensive medications such as diuretics or beta-blockers 1

Off-Label Uses with Strong Evidence

PTSD-Related Nightmares

• Prazosin is an alpha-1 adrenergic receptor antagonist that reduces CNS sympathetic outflow throughout the brain, making it effective for treating PTSD-associated nightmares 2
• Multiple randomized controlled trials demonstrate prazosin's efficacy in reducing nightmare frequency and intensity in both military veterans and civilians with PTSD 2
• The American Academy of Sleep Medicine supports its use for PTSD-related nightmares, though a recent contradictory study has led to a downgrading of the recommendation strength 2

Dosing for PTSD Nightmares

• For civilians with PTSD-related nightmares, the average effective dose is approximately 3-4 mg/day 3
• Military veterans typically require higher doses, ranging from 9.5-15.6 mg/day 3
• Treatment should start with 1 mg at bedtime to minimize first-dose hypotension risk, then gradually increase by 1-2 mg every few days until clinical response is achieved 3

Other Established Off-Label Use

• Benign prostatic hyperplasia (BPH) - Prazosin's alpha-1 blockade helps relieve obstructive and irritative symptoms by relaxing smooth muscle in the prostate 4
• Approximately 60-70% of BPH patients experience symptom improvement with prazosin therapy, including improved urinary flow rates and decreased urethral pressure 4

Side Effects and Precautions

• Common side effects include dizziness, lightheadedness, and transient orthostatic hypotension, especially after initial doses 3
• First-dose hypotension can be minimized by starting with a low dose (1 mg) and taking the medication at bedtime 3, 1
• Rare but serious side effect: priapism has been reported, particularly with rapid dose titration 5
• If discontinued, PTSD-related nightmares may return to baseline intensity 2

Special Considerations

• Patients taking selective serotonin reuptake inhibitors (SSRIs) may have a diminished response to prazosin for PTSD symptoms 3
• Blood pressure should be monitored after the initial dose and with each significant dose increase 3
• For severe PTSD cases, especially in military personnel, higher doses (up to 30-45 mg in some case reports) and divided dosing may be considered 6

Monitoring Parameters

• Blood pressure monitoring is essential, particularly after initial dosing and dose increases 3
• Assessment of nightmare frequency and intensity using standardized measures when possible 3
• Monitor for orthostatic hypotension, especially early in therapy 7

Prazosin offers a valuable treatment option for both its FDA-approved indication of hypertension and its well-established off-label use for PTSD-related nightmares, with a generally favorable side effect profile when properly titrated.