[ In Brief: Prazosin decreases nightmares, improves quality of sleep and decreases overall PTSD symptoms in active-duty soldiers. It is well tolerated.]
Nightmares related to the trauma are experienced by most people with PTSD. There are no medications approved for treating nightmares, though trazodone, prazosin, clonidine and sedating antipsychotics are frequently prescribed. Of these, prazosin is the best studied and has the most support.
In the September, 2013 issue of The American Journal of Psychiatry, prazosin is compared to placebo in the treatment of nightmares and PTSD in active-duty combat veterans. The trial was double-blind and randomized. Primary outcome measures were severity of nightmares, quality of sleep and overall PTSD symptom levels. Prazosin was superior to placebo on all three measures, to a significant extent. Nightmare severity decreased by about 50% in those taking prazosin, and it was associated with marked or moderate improvement in global illness severity in 64% (versus 27% of those on placebo) an NNT of 3 (Number Needed to Treat). This mean only 3 people needed to be treated for 1 person to have a moderate or marked response, which is pretty good for psychiatric medications (and pharmacotherapy in the rest of medicine). However, only 3 patients on prazosin went into remission, versus 0 on placebo; so most patients were still symptomatic. Prazosin was not an effective treatment for most people in and of itself.
There were no differences overall in the number of patients experiencing side effects, which were generally mild and transient. There was 1 episode of brief syncope (passing out due to insufficient blood supply to the brain). This is a well known side effect of prazosin; if it occurs, it is usually with the first dose or very early in treatment. Other side effects included (with the percentage of those on prazosin listed first): lightheadedness (25% vs 20%), nasal congestion (22% vs 11%), lack of energy (0% vs 3%), drowsiness (3% vs 9%), depression (0% vs 6%). There were no changes in blood pressure. Headaches were significantly less common with prazosin.
I have prescribed prazosin a few times, without much success. After reading this article, I think the most likely reason for that is the much lower dose at which I was prescribing it. In this study, prazosin was given twice a day; For men, final doses were 4 mg mid morning and 15.6 mg at night; for women, final doses were 1.7 mg mid morning and 7 mg at night. The authors point out that women should be treated with lower doses due to greater sensitivity to the medication, and that the drug’s short half-life indicates it is likely to be more effective if taken twice a day. The medication was titrated over the course of 5 weeks to get to the final dose, to decrease the risk of syncope.
Conclusion: prazosin is an effective medication for decreasing nightmares, improving sleep and lessening PTSD symptoms. It is well tolerated when titrated slowly. Most patients still have substantial symptoms after a trial of prazosin, and should also be offered evidence-based treatment, such as exposure therapy. It is unknown how long prazosin should be continued. Side effects are likely to decrease over time, and the medication is generic and relatively inexpensive.
A Trial of Prazosin for Combat Trauma PTSD With Nightmares in Active-Duty Soldiers Returned From Iraq and Afghanistan
Am J Psychiatry 2013;170:1003-1010. doi:10.1176/appi.ajp.2013.12081133