From the Guidelines
Prazosin is effective in reducing nightmare frequency and intensity by blocking alpha-1 adrenergic receptors in the brain, which helps reduce excessive norepinephrine activity associated with trauma-related nightmares, particularly in PTSD. The medication works by reducing CNS sympathetic outflow throughout the brain, which regulates several CNS phenomena implicated in the pathogenesis of PTSD, including sleep and nightmare phenomena 1. Typically, treatment begins with a low dose of 1mg at bedtime, gradually increasing to 3-15mg as needed while monitoring for side effects, with a mean dosage of 9.5 ± 0.5 mg/day showing efficacy in reducing PTSD-associated nightmares 1.
The medication takes effect within days to weeks, with patients often reporting decreased nightmare frequency and intensity, as well as improved sleep quality. Prazosin specifically targets the brain's fear response system without causing sedation or addiction, making it different from traditional sleep medications. Common side effects include dizziness and low blood pressure, especially when first standing up, so patients should take the first dose when they can remain lying down and should rise slowly from bed. While prazosin doesn't cure the underlying trauma, it provides symptomatic relief by dampening the neurochemical processes that trigger nightmares during sleep, allowing for more restorative rest and improved daytime functioning.
Some key points to consider when using prazosin for nightmares include:
- Starting with a low dose and gradually increasing as needed
- Monitoring for side effects, particularly dizziness and low blood pressure
- Taking the first dose when able to remain lying down and rising slowly from bed
- Considering the individual circumstances of the patient and accessible treatment options. Prazosin is recommended for the treatment of PTSD-associated nightmares and nightmare disorder, and may be used in conjunction with other therapies such as image rehearsal therapy, cognitive behavioral therapy, and exposure, relaxation, and rescripting therapy 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Mechanism of Action
- Prazosin is a centrally and peripherally acting alpha(1)-adrenergic antagonist 2
- The drug blocks central alpha1-adrenergic activity, which is associated with fear and startle responses 3
- Prazosin decreases noradrenaline effects at brain α-1 adrenoreceptors, which may be associated with hyperarousal, trauma nightmares, and sleep disturbances in PTSD subjects 4
Efficacy in Reducing Nightmares
- Prazosin has been shown to be effective in reducing PTSD-related nightmares in several studies 2, 3, 5, 4, 6
- The drug has been found to reduce distressing dreams in PTSD patients, with a significant difference compared to placebo 4
- Prazosin has been shown to improve sleep and reduce nightmares in patients with both combat- and noncombat-related trauma 2, 3
Dosage and Administration
- The typical starting dose of prazosin is 1 mg, with gradual increases to maintenance levels of 2-6 mg at night 5
- Higher doses (e.g., 10-16 mg at night) have been used in studies of military patients with PTSD 5
- Prazosin is usually taken at night, with monitoring for hypotension after the first dose 5
Safety and Tolerability
- Prazosin has been found to be well-tolerated, with the most frequently reported adverse event being orthostatic hypotension 2
- No significant difference in blood pressure was observed at the end of trials 6
- Prazosin has been found to be effective and well-tolerated in patients with PTSD, with a relatively rapid response within weeks 5