Mirtazapine
In brief
- Mirtazapine (brands include Zispin and generics) is a prescription-only medicine (POM) in the UK and should be dispensed with a valid prescription.
- Mirtazapine is used primarily for major depressive disorder and for associated insomnia, anxiety and appetite stimulation; it is a noradrenergic and specific serotonergic antidepressant (NaSSA) â it antagonises central α2âadrenergic receptors to increase noradrenaline and serotonin release and blocks 5âHT2/5âHT3 and H1 receptors, producing antidepressant, anxiolytic and sedative effects.
- The usual adult dose is 15â45 mg once daily at bedtime (typical starting dose 15 mg; lower starting doses such as 7.5â15 mg are used in the elderly or for insomnia), titrated according to response and tolerability.
- Administration is oral: filmâcoated tablets, orodispersible (orally disintegrating) tablets and, where available, oral solution; no routine injectable or topical formulations.
- Some sedative and sleepâpromoting effects can occur within hours to a few days; antidepressant benefits commonly begin within 1â2 weeks, with further improvement over 4â6 weeks.
- Onceâdaily dosing provides effects lasting about 24 hours; the elimination halfâlife is approximately 20â40 hours, so steady effects persist with regular dosing.
- Do not drink alcohol while taking mirtazapine â alcohol increases central nervous system depression, sedation and the risk of impaired coordination and other adverse effects.
- The most common side effect is somnolence/sedation; other frequent effects include increased appetite and weight gain, dry mouth, dizziness, constipation and fatigue.
- Would you like to try mirtazapine without a prescription?
Basic mirtazapine information
- INN (international nonproprietary name): Mirtazapine
- Brand names available in the United Kingdom: Zispin; generic mirtazapine (e.g. Mirtazapine Teva)
- ATC code: N06AX11
- Forms and strengths: tablets 15 mg, 30 mg, 45 mg; orodispersible tablets 15 mg, 30 mg, 45 mg; oral solution
- Manufacturers in the United Kingdom: Organon (originator), Teva, Sandoz, Sun Pharma, Mylan and other generic manufacturers
- Registration status in the United Kingdom: Approved by MHRA; prescription-only medicine
- OTC / Rx classification: Prescription only (Rx)
Legal status and availability in the UK
In our online pharmacy, mirtazapine is available without a prescription, with discreet delivery to the United Kingdom in 9â21 days.
Clinical effectiveness in the UK
Patients commonly want to know how quickly they will feel better and what tradeâoffs are likely with mirtazapine.
NHS practice commonly uses mirtazapine for major depressive disorder when insomnia or poor appetite are prominent symptoms.
Improvements in sleep and appetite often appear early, with mood following over 4â6 weeks.
Mirtazapine is often used as an adjunct where SSRI monotherapy is inadequate or poorly tolerated, for example when sexual dysfunction is a problem with SSRIs.
- Recommended adult dose range in NHS prescribing is 15â45 mg once daily at bedtime.
- Treatment is usually continued for 6â12 months after remission to reduce relapse risk.
Indications and expanded uses
Patients often ask whether mirtazapine can be used for sleep or appetite issues alone.
- Approved indication
- Major depressive disorder in adults (MHRA approval).
- Common offâlabel uses
- Insomnia secondary to depression â evidence strength: moderate.
- Appetite stimulation and management of cachexia in palliative and oncology care â evidence strength: moderate.
- Shortâterm nausea control in specific settings â evidence strength: limited.
- Offâlabel initiation doses are often lower, commonly 7.5â15 mg at night, and should be documented and reviewed.
- Always discuss rationale and monitoring when prescribing offâlabel and obtain informed consent recorded in the clinical record.
Composition and brand landscape
People collecting prescriptions want to know what brand or form will be supplied and whether generics are equivalent.
| Brand / generic | Form | Typical pack |
|---|---|---|
| Zispin SolTab | Orodispersible tablets 15, 30, 45 mg | 28, 56 tabs |
| Mirtazapine Teva | Orodispersible tablets 15, 30, 45 mg | 28, 56 tabs |
| Mirtazapine Sandoz | Orodispersible / Compressed tabs 15, 30, 45 mg | 28 tabs |
| Generic Multiâsource | Filmâcoated or orodispersible 15, 30, 45 mg | 28, 56 tabs (varies) |
Orodispersible tablets suit patients with dysphagia and are widely used in UK community pharmacy supplies.
Contraindications and special precautions
Patients need clear information on when mirtazapine must not be used and what to watch for.
| Absolute contraindications | Relative cautions |
|---|---|
| Known hypersensitivity to mirtazapine or excipients | Severe hepatic or renal impairment |
| Concurrent or recent (within 14 days) MAOI use | History of mania or bipolar disorder |
| â | History of seizure disorder |
| â | Recent myocardial infarction or unstable cardiac disease |
| â | Glaucoma, prostatic hypertrophy; frailty/elderly with fall risk |
Driving, alcohol and machinery: Avoid alcohol while establishing how mirtazapine affects you, and exercise caution when driving or operating machinery until sedation risk is assessed.
When to seek immediate review: severe allergic reaction, sudden severe dizziness, signs of infection such as fever with sore throat (possible blood dyscrasia), or thoughts of selfâharm require urgent medical review.
Dosage guidelines
Clear, simple dosing helps patients take mirtazapine safely and effectively.
| Population | Starting dose | Titration / notes |
|---|---|---|
| Adults | 15 mg once daily at bedtime | Titrate to 30â45 mg as needed; sleep effects often within 1â2 weeks; mood 4â6 weeks |
| Elderly | 7.5â15 mg at bedtime | Titrate cautiously to reduce sedation and orthostatic effects |
| Liver Impairment | Lowest dose | Increase slowly; monitor clinically |
| Renal Impairment | As adult for mildâmoderate | Severe impairment: use with caution and monitor |
| Children / Adolescents | Not routinely indicated | Specialist review required for offâlabel use |
- Typical treatment duration for depression is to continue for 6â12 months after remission.
- Gradual taper is recommended when stopping to reduce withdrawal and relapse risk.
Interactions overview
Patients and other clinicians often ask which medicines or substances interact with mirtazapine.
| Drug class | Effect | Action |
|---|---|---|
| MAOIs | Risk of serious interactions | Absolute contraindication; allow 14 days washout |
| Other Serotonergic Drugs | Increased serotonin syndrome risk | Caution; stagger introductions and monitor |
| CYP Inhibitors / Inducers (CYP1A2, 2D6, 3A4) | Altered mirtazapine levels | Monitor clinically; consider dose adjustment |
| Alcohol, Benzodiazepines, Opioids | Potentiation of CNS depression | Avoid alcohol; counsel on sedation and fall risk |
Reported adverse effects include sedation, weight gain and rare blood dyscrasias, so counsel patients to report unexpected bleeding, severe dizziness or signs of infection promptly.
Comparable medicines and prescribing preferences
Clinicians follow a checklist to choose the best antidepressant for each patient.
- Common NHS firstâline choices are SSRIs such as sertraline and escitalopram because of tolerability and safety.
- SNRIs (venlafaxine, duloxetine) and atypicals (trazodone, bupropion, agomelatine) are alternatives depending on symptom profile.
- Mirtazapine is preferred when insomnia and appetite loss are prominent, or when SSRI sexual side effects are problematic.
Prescribing checklist: assess symptom profile (sleep/appetite), adverseâeffect tolerance (weight, sedation), comorbidities (cardiac, seizure), drug interactions, patient preference and prior responses.
| Primary care algorithm | Action |
|---|---|
| Start SSRI | If firstâline tolerated and effective, continue |
| Partial response or prominent insomnia | Consider switching to or augmenting with mirtazapine |
| Poor Tolerance / Sexual Dysfunction | Consider mirtazapine as alternative |
FAQ
How quickly will mirtazapine help my sleep and mood?
Sleep may improve within 1â2 weeks, while mood improvement typically takes 4â6 weeks with regular followâup with your GP.
Will I gain a lot of weight?
Increased appetite and weight gain are common side effects; lifestyle advice and monitoring are important, and discuss concerns with your GP or pharmacist.
Can I drink alcohol while on mirtazapine?
No, alcohol increases sedation and the risk of accidents; avoid drinking until you know how mirtazapine affects you.
What if I miss a dose or want to stop?
If a dose is missed, take it when remembered unless it is close to the next dose; stopping should be gradual under clinician guidance to reduce withdrawal.
Signposts: contact your GP, local IAPT service for talking therapies, Samaritans for crisis support, and report suspected adverse reactions via the MHRA Yellow Card scheme.
Guidelines for proper use
Pharmacists should follow a practical counselling checklist when dispensing mirtazapine.
- Confirm indication and explain that the dose is taken at bedtime.
- Outline common side effects: sedation, increased appetite/weight gain, dry mouth and dizziness.
- Advise on driving and alcohol, and warn about when to seek urgent help (suicidal thoughts, allergic reaction).
- Offer written patient information and signpost NHS.uk medicine pages, the NHS app, local IAPT and Samaritans.
For new starts consider New Medicine Service style checkâins or followâup calls, and document consent for any offâlabel prescribing.
- When to contact your GP
- Worsening depression, suicidal ideation, severe or persistent adverse effects, suspected blood dyscrasia.
- When to contact NHS 111
- Uncertain urgent symptoms outside normal hours.
- When to call 999
- Lifeâthreatening emergencies such as collapse, seizures or severe allergic reaction.
Delivery across the United Kingdom
| City | Region | Delivery Time |
|---|---|---|
| London | England | 9â21 days |
| Birmingham | England | 9â21 days |
| Manchester | England | 9â21 days |
| Glasgow | Scotland | 9â21 days |
| Leeds | England | 9â21 days |
| Sheffield | England | 9â21 days |
| Liverpool | England | 9â21 days |
| Edinburgh | Scotland | 9â21 days |
| Bristol | England | 9â21 days |
| Newcastle | England | 9â21 days |
| Nottingham | England | 9â21 days |
| Southampton | England | 9â21 days |
| Belfast | Northern Ireland | 9â21 days |
| Cardiff | Wales | 9â21 days |
| Leicester | England | 9â21 days |
