Tetracyclic antidepressant Pregnancy: Do not use during pregnancy unless there are compelling reasons. There is no evidence of safety in human pregnancy; animal studies have not shown hazard. Mianserin is contraindicated during breast-feeding — breast-feeding should be discontinued if treatment with mianserin is considered essential.

Mianserin hydrochloride

Mianserin is a tetracyclic antidepressant used in the treatment of depressive illness.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 30 mg or 40 mg per day initially, increasing gradually as necessary; the effective dosage usually lies between 30 mg and 90 mg

Route: Oral (tablets swallowed whole without chewing)

Frequency: In divided doses, or as a single dose at night (due to the favourable effect on sleep)

Max: No explicit maximum stated. §4.2 states only: 'Divided doses of up to 200 mg are well tolerated.'

SPC §4.2 (Mianserin 10 mg film-coated tablets): 'Treatment should usually commence with 30 mg or 40 mg mianserin per day increasing gradually as necessary. The effective dosage usually lies between 30 mg and 90 mg. Divided doses of up to 200 mg are well tolerated.' It is often advantageous to maintain antidepressant treatment for several months after clinical improvement has occurred, and 'in order to ensure an optimal antidepressant effect the dosage of mianserin should not be reduced'. OLDER PEOPLE: use is restricted to patients over 65 who (a) do not respond to other antidepressant drugs, (b) have glaucoma, or (c) have prostatic hypertrophy — not more than 30 mg a day initially; a lower than normal maintenance dose may be sufficient. Pharmacokinetic studies in the elderly suggest a longer half-life and slower metabolic clearance, implying a single night-time dose is preferable to divided dosing in older people. PAEDIATRIC: 'Mianserin should not be used in the treatment of children and adolescents under the age of 18 years' (§4.2/§4.4) — no paediatric dose is given in this source. MONITORING (§4.4): mianserin has been associated with haematological and hepatic reactions; a full blood count is recommended every 4 weeks during the first 3 months of treatment, and treatment should be stopped with an FBC obtained if fever, sore throat, stomatitis or other signs of infection develop. Improvement in depression may not occur during the first 2–4 weeks — monitor closely during this period. Care in patients with recent myocardial infarction, heart block or arrhythmia.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Mania
Severe liver disease
Breast-feeding (stated as contraindicated in §4.6)

Side effects

Bone marrow depression, usually presenting as granulocytopenia or agranulocytosis (most commonly after 4–6 weeks, generally reversible on stopping); leucopenia and aplastic anaemia
Hyponatraemia (usually in the elderly)
Dizziness, tremor; convulsions have been reported at therapeutic dosage (withdraw treatment)
Postural hypotension
Disturbances of liver function; jaundice, usually mild (withdraw treatment)
Skin rash, sweating; arthralgia, polyarthropathy, arthritis; oedema

Clinical monograph

How it works

It enhances central noradrenergic transmission largely through antagonism of presynaptic alpha-2 adrenoceptors, and also blocks several serotonin and histamine receptors.

Prescribing in practice

Mianserin can cause bone marrow suppression including agranulocytosis, so any signs of infection such as fever, sore throat or stomatitis should prompt an urgent full blood count and review.
It is sedating, which may be useful where insomnia accompanies depression but increases the risk of drowsiness and falls, particularly in older people.
As with all antidepressants, monitor for suicidal thoughts and behaviour, especially early in treatment and in younger adults.

Monitoring

A full blood count should be checked if signs of infection develop, and patients should be monitored for mood changes and emergent suicidal ideation during treatment.

Counselling the patient

Report any fever, sore throat, mouth ulcers or other signs of infection without delay.
This medicine can make you drowsy, so take care with driving and alcohol.
Do not stop the medicine abruptly; your prescriber will advise on tapering.

Evidence & guidelines

Mianserin is an established antidepressant, and the requirement to investigate signs of infection because of the risk of blood dyscrasias is reflected in its product information.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways