What are the recommended doses of doxazosin and terazosin (alpha-1 blockers) for treating nightmares in Post-Traumatic Stress Disorder (PTSD)?

Recommended Doses for Doxazosin and Terazosin for PTSD-Related Nightmares

Critical Evidence Gap

Neither doxazosin nor terazosin are mentioned in the American Academy of Sleep Medicine guidelines for treating nightmares, and terazosin has no published evidence for this indication. 1 The guidelines specifically recommend prazosin as the established alpha-1 blocker for PTSD-associated nightmares, with other medications having only Level C evidence or lower. 1, 2

Doxazosin Dosing (Off-Label, Emerging Evidence)

While not guideline-recommended, emerging research suggests doxazosin may be effective:

Starting and Target Doses

• Start at 4 mg once daily at bedtime (particularly with the GITS formulation, which minimizes first-dose hypotensive effects). 3
• Effective dose range: 4-8 mg daily, with 8 mg showing superior efficacy (55.2% nightmare-free nights vs. 4.3% without medication). 4
• The mean effective dose in a 51-patient chart review was not specifically reported, but patients were successfully treated over 12 weeks with significant nightmare reduction. 5

Advantages Over Prazosin

• Longer half-life allows once-daily dosing (versus prazosin's 6-8 hour duration requiring multiple doses). 3
• Better absorption profile minimizes hypotensive adverse effects compared to prazosin. 3
• Fewer side effects, with dizziness being the primary complaint but generally well-tolerated. 4

Clinical Outcomes

• 25% of patients achieved complete remission of nightmares at 12 weeks in the largest case series. 5
• Significant improvement in CAPS B2 scores (nightmare measure) and overall trauma-related sleep symptoms. 5

Terazosin: No Evidence

Terazosin has zero published evidence for treating nightmares and is not mentioned in any PTSD nightmare treatment guidelines or research studies. 1 There is no basis for recommending dosing for this indication.

Guideline-Recommended Alternative: Prazosin

If you choose to use an alpha-1 blocker with established evidence:

• Start at 1 mg at bedtime, increase by 1-2 mg every few days until clinical response. 1, 2
• Effective doses: 3-4 mg/day for civilians, 9.5-15.6 mg/day for military veterans (higher doses often needed in combat-related PTSD). 1, 2
• Level A recommendation from the American Academy of Sleep Medicine for PTSD-associated nightmares. 1

Critical Monitoring

• Monitor blood pressure after initial dose and with each significant dose increase for all alpha-1 blockers. 2, 6
• Watch for orthostatic hypotension, the primary limiting side effect. 1
• Expect return of nightmares to baseline if medication is discontinued. 2, 6

Clinical Decision Algorithm

1. First-line: Image Rehearsal Therapy (IRT) is the guideline-recommended first-line treatment. 1, 2, 6
2. If pharmacotherapy needed: Prazosin is the only alpha-1 blocker with Level A evidence. 1, 2
3. If prazosin fails or causes intolerable side effects: Consider doxazosin 4-8 mg daily based on emerging evidence, though this remains off-label. 5, 4, 3
4. Terazosin: Do not use - no evidence exists for this indication.