Mianserin, sold under the brand name Tolvon among others, is an atypical antidepressant that is used primarily in the treatment of depression in Europe and elsewhere in the world.

Mianserin is closely related to mirtazapine, both chemically and in terms of its actions and effects, although there are significant differences between the two drugs (for example, its higher noradrenergic activity and lower 5-HT3 receptor antagonism).

If based on clinical decision, normal precautions should be exercised and the dosages of mianserin and any concurrent therapy kept under review and adjusted as needed.

[5][6] Common (1% < incidence ≤ 10%) adverse effects include drowsiness during maintenance therapy, tremor, headache, dizziness, vertigo, and weakness.

[5] Abrupt or rapid discontinuation of mianserin may provoke a withdrawal, the effects of which may include depression, anxiety, panic attacks,[10] decreased appetite or anorexia, insomnia, diarrhea, nausea and vomiting, and flu-like symptoms, such as allergies or pruritus, among others.

[40] By antagonizing the somatodendritic and presynaptic α2-adrenergic receptors, which function predominantly as inhibitory autoreceptors and heteroreceptors, mianserin disinhibits the release of norepinephrine, dopamine, serotonin, and acetylcholine in various areas of the brain and body.

[citation needed] It was developed but not discovered by Organon International; the first patents were issued in The Netherlands in 1967, and it was launched in France in 1979 under the brand name Athymil, and soon thereafter in the UK as Norval.

Its generic name in French and its DCFTooltip Dénomination Commune Française are miansérine, in Spanish and Italian and its DCITTooltip Denominazione Comune Italiana are mianserina, and in Latin is mianserinum.

It is also available throughout the world under a variety of other brand names including Athymil, Bonserin, Bolvidon, Deprevon, Lantanon, Lerivon, Lumin, Miansan, Serelan, Tetramide, and Tolvin among others.