Mirtazapine and Alcohol: Sedation Is the Risk, Not Poisoning

Mirtazapine and alcohol do not react to produce a toxic compound. What they do is add up. Both depress the central nervous system, so the combination makes you more drowsy, less coordinated and less able to judge how impaired you are. The NHS advises against drinking on mirtazapine for that reason, and the licensed label goes further and says avoid it.

If you are in crisis, call your local emergency number. In the UK that is 999, or NHS 111 for urgent advice, and the Samaritans can be reached free on 116 123 at any hour. In Australia, call 000, or Lifeline on 13 11 14.

What the NHS and the label actually say, and where they differ

They are close, but not identical, and the gap tells you something.

The NHS page on mirtazapine says: “It’s best not to drink alcohol when taking mirtazapine because it can increase the risk of side effects, such as making you feel very drowsy.” That is guidance, hedged, aimed at a person managing their own life.

The UK Summary of Product Characteristics is firmer: “Mirtazapine may increase the CNS depressant effect of alcohol. Patients should therefore be advised to avoid alcoholic beverages while taking mirtazapine.”

The same label lists mirtazapine’s effect on driving as minor to moderate, noting that it may impair concentration and alertness particularly in the initial phase of treatment, and advising patients to avoid dangerous tasks at any time when affected. Note the phrase “particularly in the initial phase”.

The mechanism is addition, not reaction

This is worth being precise about, because people confuse it with metronidazole.

There is no disulfiram-like reaction here. Nothing in mirtazapine blocks the enzyme that clears alcohol, and no flushing reaction is described in the label. What happens instead is that two central nervous system depressants are in your body at the same time and their effects stack.

Mirtazapine is strongly sedating, which is why it is usually taken at night and why the NHS lists feeling drowsy or sleepy first among its common side effects. Add alcohol, which is also sedating, and you get more of the same thing: deeper drowsiness, worse coordination, poorer judgement, and, crucially, less accurate self-assessment of all three.

The label also flags that mirtazapine may increase the sedating properties of benzodiazepines, opioids, most antipsychotics and antihistamines. If any of those are in the mix as well, the arithmetic gets worse.

What the driving research shows, including the part that cuts against the warning

Two on-the-road studies are more informative than the label wording, and both contain something inconvenient.

Ramaekers, reviewing a decade of standardised on-the-road driving tests in 2003, reported that acute doses of sedating antidepressants produced weaving comparable to drivers at a blood alcohol concentration of 0.8 mg/mL or more. That is the alarming half. The other half is that nocturnal doses of mirtazapine did not produce residual driving impairment when measured the next day, and that driving performance generally returned to placebo levels after a week of treatment.

Van der Sluiszen and colleagues, in 2021, tested long-term users of sedating antidepressants, including 25 people taking mirtazapine, against 65 healthy controls in an hour of real highway driving. Across all long-term users the increase in weaving was neither statistically significant nor clinically relevant. But those treated for less than three years did show a significant and clinically relevant increase, benchmarked against a blood alcohol concentration of 0.5 mg/mL.

Neither finding makes drinking on mirtazapine safe. The impairment you are adding alcohol to is not a fixed quantity, and you cannot calibrate it from how a friend on the same medicine copes.

If you are here looking for permission to stop taking it

Some people arrive at this page because they want to drink at a wedding, a holiday or a funeral, and are wondering whether to skip their mirtazapine to make that possible.

Say it out loud to your prescriber instead. That is not a brush-off, it is the actual answer, and here is why it cannot come from a website.

Mirtazapine should not be stopped suddenly. The NHS is explicit: do not stop taking it abruptly because it can cause withdrawal symptoms, and speak to your doctor first if you want to stop. The label describes withdrawal reactions after abrupt termination following long-term use, most commonly dizziness, agitation, anxiety, headache and nausea, and says treatment should be discontinued gradually.

The Royal College of Psychiatrists makes the same point and adds the one people miss: stopping suddenly can also increase the chance of becoming unwell again. Everyone should taper, they say, and how quickly depends on the person.

We are not going to publish a schedule, a step or a timescale, because the right one depends on how long you have taken it, at what dose, why it was started and what happened last time. That decision belongs to the person who prescribed it. What we will say plainly is that skipping doses so you can drink is the worst version of both options: you get withdrawal effects and you get a night of drinking on a nervous system that is already destabilised.

Does mirtazapine help people drink less?

A fair question, and the honest answer is no, on the evidence available.

Cornelius and colleagues, 2016, reviewed the literature on mirtazapine in co-occurring major depression and alcohol use disorder, covering four of their own small studies and two conducted outside the United States. They found mirtazapine well tolerated in that group and some evidence that it reduced depressive symptoms, possibly quite quickly. They found no evidence of effectiveness for decreasing the level of alcohol ingestion.

Their double-blind placebo-controlled pilot trial the same year reached the same place. Between-group differences in depression, alcohol consumption and craving were all non-significant, possibly because the sample was small. Within the mirtazapine group, depressive symptoms fell significantly by week two and stayed down, while the placebo group showed no significant fall until week eight. On alcohol, the finding was flat: no evidence of efficacy for reducing consumption.

A separate randomised controlled trial by de Bejczy and Söderpalm in 2015, in 59 male high consumers of alcohol, also failed to show an advantage over placebo on the intention-to-treat analysis, though the authors suggested a possible benefit in the subgroup with a family history of alcohol use disorder.

So mirtazapine may be a reasonable antidepressant for someone who also drinks heavily. It is not a treatment for the drinking.

Where this stops being about drowsiness

Two things belong on a page like this, and most pages leave them out.

In overdose, mirtazapine alone usually produces relatively mild effects, according to its label: central nervous system depression, disorientation, prolonged sedation, a fast heart rate. The label then adds that more serious outcomes, including fatalities, are possible at much higher doses and “especially with mixed overdoses”.

Separately, depression itself carries an increased risk of suicidal thoughts and self-harm, and the label notes that risk persists until significant remission occurs, with particular monitoring advised early in treatment. Alcohol lowers inhibition and worsens mood. The Royal College of Psychiatrists states that drinking alcohol can make an existing mental health problem “much worse” and can increase the risk of self-harm and suicide.

If you are having thoughts of harming yourself, contact emergency services where you are. In the UK, call 999 or NHS 111, or the Samaritans free on 116 123. In Australia, call 000, or Lifeline on 13 11 14.

When the drinking is the thing that needs treating

Being told not to drink on an antidepressant is an ordinary inconvenience for most people. For some, it is the moment they realise they cannot comply, and that is worth more attention than the pharmacology.

The early signs of alcohol dependence and what a functioning drinker looks like are reasonable places to start reading. If you drink heavily every day, do not stop abruptly on your own, because unmanaged alcohol withdrawal can be dangerous. Speak to a clinician first.

The Orchid Recovery is a residential addiction and mental health treatment centre in Hang Dong District, Chiang Mai, Thailand, for international English speaking adults. Where depression and drinking are tangled together, both need treating, which is what dual diagnosis means. Our pages on depression treatment and alcohol addiction treatment explain what we do, our clinical team is listed here, and you can talk to us. We do not adjust anyone’s antidepressant remotely, and we would not do so on the basis of a page like this. Most people reading this need their prescriber, not us.

Sources

• NHS, Mirtazapine
• electronic Medicines Compendium, Mirtazapine 30mg Tablets, Summary of Product Characteristics
• Royal College of Psychiatrists, Stopping antidepressants
• Royal College of Psychiatrists, Alcohol, mental health and the brain
• Ramaekers JG, Antidepressants and driver impairment: empirical evidence from a standard on-the-road test, Journal of Clinical Psychiatry 2003
• van der Sluiszen NNJJM et al, Driving performance and neurocognitive skills of long-term users of sedating antidepressants, Human Psychopharmacology 2021
• Cornelius JR et al, A Review of the Literature of Mirtazapine in Co-Occurring Depression and an Alcohol Use Disorder, Journal of Addictive Behaviors, Therapy and Rehabilitation 2016
• Cornelius JR et al, Mirtazapine in comorbid major depression and an alcohol use disorder: a double-blind placebo-controlled pilot trial, Psychiatry Research 2016
• de Bejczy A and Söderpalm B, The effects of mirtazapine versus placebo on alcohol consumption in male high consumers of alcohol, Journal of Clinical Psychopharmacology 2015
• Samaritans, Contact a Samaritan