Mirtazapine Induces Nightmares in Depressed Patients

In daily routine clinical practice, it appears that patients with depressive symptoms suffer more from nightmares while being treated with (often low-dose) mirtazapine than patients treated with another antidepressant. This phenomenon occurred especially during the phase of increasing the dose from 7.5 mg to and 22.5 mg of mirtazapine. While being treated with the maintenance dose (between 30 and 45 mg) for several days, the patients then reported disappearing of this specific side effect. The package information leaflet of mirtazapine includes the side effect of „vivid dreams“ in 1 of 10 patients and nightmares in 1 of 100 patients. During clinical visitation round about a fourth of the patients that were new to the treatment with mirtazapine reported nightmares without being questioned about this subject. Even more suffered from nightmares after being specifically asked whether this side-effect would have been appeared. Mirtazapine shows to be very useful in the treatment of depressions with symptoms of insomnia because of its sleep-promoting effects. Paradoxically, the sleep-promoting effects occur only in low-dose treatment. At this moment, only two articles describe a similar subject [ 1 ] [ 2 ]. These case reports involve a 21-year-old and a 52-year-old male patient being treated for depressive symptoms with 15 mg of mirtazapine. Each patient showed new occurring nightmares while taking mirtazapine. This seems to be congruent to the observations during clinical practice as described above. While it is known that it frequently produces sleep related symptoms like a restless legs syndrome, there is only little literature about parasomnias as a side effect of mirtazapine. Mirtazapine has in contrast to many other antidepressants no REM-sleep repressing effect. There are a few cases that describe REM-behavior-disease and somnambulism in the use of mirtazapine. To sum up, while seen during clinical routine that there are cases in which mirtazapine produces nightmares, there is only little literature that deals with this specific side effect. Since mirtazapine is used quite common in patients with depressive symptoms with sleep disorders as well as a sleeping drug in patients with or without other specific psychiatric diagnoses, nightmares as side effect of low-dose mirtazapine should be carefully regarded and evaluated in patients whose compliance otherwise decreases because of this particular and subjectively often severe effect.