Prescription Mirtazapine Drug Information
Common side effects of mirtazapine include drowsiness, sedation, malaise/lassitude, dry mouth, dizziness, increased appetite, and weight gain. Less common side effects include agitation, aggression, rash, restless legs syndrome (RLS), strange, vivid, and even lucid dreams, and weak psychedelic effects, including auditory and visual hallucinations. Most of these side effects are generally mild and become less prominent with consistent dosing over time Rare and serious side effects may include facial edema, allergic reaction, bone marrow toxicity, myelodysplasia, syncope, seizures, and agranulocytosis (occurs in 1/1,000 patients) Mirtazapine does not cause most of the side effects encountered with the SSRIs and related drugs such as sexual dysfunction, insomnia, nausea, vomiting, diarrhea, urinary retention, mydriasis, bruxism, cognitive/memory impairment, and/or emotional blunting (apathy/anhedonia), nor does it have the capacity to exacerbate a patient's depressive/anxious symptoms or cause suicidal ideation.
Mirtazapine has mild psychedelic effects which are occasionally encountered by some of its patients. Reports include vivid, bizarre, or even lucid dreams, and auditory and visual hallucinations. These effects tend to be most prominent upon first commencing treatment and usually dissipate with time. They are especially prominent when mirtazapine is taken acutely, taken at high doses, or mixed with cannabis. Because of these properties, mirtazapine has seen a miniscule degree of recreational use, though most of the people that abuse it find the experience unpleasant on account of mirtazapine's lack of relative positive euphoria, strong sedating effects, and tendency to induce restless legs syndrome (RLS) at higher doses.
The mechanism of action of these effects is currently unknown, but due to the fact that they seem to be very similar to those of 5-HT2A receptor
-mediated serotonergic psychedelics
such as LSD
and magic mushrooms
, it has been suggested that mirtazapine does not function as a true zero intrinsic activity silent antagonist
at the 5-HT2A
receptor, but is actually a weak partial agonist
with low intrinsic activity.
This may sufficiently explain the weak nature of the effects, their tendency to fade away with time via tolerance
, and mirtazapine's ability to block the effects of other 5-HT2A