Tapering 20mg Prazosin at Bedtime
Reduce prazosin by 10-25% of the current dose every 1-2 weeks, monitoring for rebound nightmares and blood pressure changes, with the understanding that nightmares frequently return to baseline intensity when prazosin is discontinued.
Key Clinical Considerations
The evidence shows that veterans responsive to prazosin frequently returned to their baseline nightmare intensity when prazosin was discontinued 1. This is a critical point—expect symptom recurrence and plan accordingly with the patient before initiating the taper.
Recommended Tapering Protocol
Week-by-Week Approach
Starting from 20mg at bedtime:
- Weeks 1-2: Reduce to 16-18mg (10-20% reduction)
- Weeks 3-4: Reduce to 14-15mg
- Weeks 5-6: Reduce to 12mg
- Weeks 7-8: Reduce to 10mg
- Weeks 9-10: Reduce to 8mg
- Weeks 11-12: Reduce to 6mg
- Weeks 13-14: Reduce to 4mg
- Weeks 15-16: Reduce to 2mg
- Weeks 17-18: Reduce to 1mg
- Week 19+: Discontinue
This proportionate reduction approach (rather than linear fixed-dose reductions) minimizes withdrawal effects by producing more consistent changes in pharmacological activity 2.
Critical Monitoring Parameters
What to Watch For:
- Rebound nightmares: The primary concern—may return rapidly after dose reduction 1
- Blood pressure changes: Monitor for rebound hypertension, though this is less common than nightmare recurrence
- Sleep quality deterioration: Assess for worsening insomnia
- PTSD symptom exacerbation: Overall symptom severity may worsen
When to Slow or Pause the Taper:
- If nightmares return to pre-treatment frequency
- If sleep quality significantly deteriorates
- If overall PTSD symptoms markedly worsen
- If patient experiences significant distress
Important Caveats
The taper can be slower if needed. Some patients may require months to successfully discontinue, with dose reductions every 2-4 weeks rather than weekly. The rate should be adjusted based on symptom tolerance 3.
Consider the reason for discontinuation. If prazosin is being stopped due to lack of efficacy (as suggested by recent large VA trials showing no benefit 1), the taper can potentially be faster. However, if it was effective and is being stopped for other reasons (side effects, patient preference), expect symptom return and taper more cautiously.
Very small final doses may be necessary. As you approach discontinuation, some patients may need doses smaller than 1mg to make the final step tolerable. Liquid formulations or compounded preparations can facilitate this 2.
Alternative Strategy
If rapid symptom recurrence occurs during tapering, consider:
- Returning to the last tolerated dose
- Implementing trauma-focused psychotherapy (CBT-I or trauma-focused CBT) concurrently with the taper to address underlying symptoms 1, 4
- Extending the taper timeline to 3-6 months or longer
- Accepting that some patients may require long-term maintenance therapy
The FDA label provides dosing guidance for initiation and titration but does not specifically address discontinuation protocols 5. Clinical practice must therefore rely on the pharmacological principle of gradual dose reduction and the clinical observation that abrupt discontinuation leads to rapid symptom return 1.