Mirtazapine withdrawal: what to expect and how to taper safely

Mirtazapine withdrawal (also called discontinuation syndrome) occurs when the medicine is stopped too quickly or abruptly after regular use.

The body has adapted to the presence of mirtazapine, and removing it suddenly causes a temporary imbalance in neurotransmitter systems.

Why it happens:

During treatment, the brain adjusts to mirtazapine's effects on noradrenaline, serotonin and histamine receptors. When the drug is removed:

• Noradrenergic rebound: sudden changes in noradrenaline levels can cause anxiety, agitation and flu-like symptoms
• Serotonergic readjustment: disrupted serotonin signalling may lead to mood disturbance, irritability and sensory symptoms
• Histamine rebound: the loss of antihistamine activity can cause insomnia and restlessness

Who is at risk:

• Anyone who has taken mirtazapine for more than a few weeks
• Patients on higher doses (30 to 45 mg) may experience more pronounced withdrawal
• Those with a history of antidepressant discontinuation problems
• Patients who are more sensitive to medication changes

Withdrawal is not the same as relapse of depression, though it can be difficult to distinguish the two in the early days. Your GP can help differentiate between the two.

The symptoms of mirtazapine withdrawal vary between individuals but typically include a combination of physical and psychological effects.

Physical symptoms:

• Dizziness and lightheadedness: often the most noticeable symptom
• Nausea and vomiting: may range from mild queasiness to pronounced sickness
• Headaches: tension-type headaches are common
• Flu-like symptoms: muscle aches, sweating, chills and fatigue
• Paraesthesia: tingling, numbness or "electric shock" sensations (sometimes called "brain zaps")
• Tremor: mild shaking of the hands
• Sleep disturbance: vivid dreams, nightmares or difficulty falling asleep (rebound insomnia)

Psychological symptoms:

• Anxiety and agitation: a heightened sense of nervousness or restlessness
• Irritability: feeling easily frustrated or short-tempered
• Low mood: can be confused with depressive relapse
• Crying spells: emotional lability is common in the early days
• Difficulty concentrating: feeling mentally foggy

Less common symptoms:

• Changes in appetite (often decreased, the opposite of what mirtazapine caused)
• Diarrhoea
• Hypomania or mania (rare, but reported)

The severity of withdrawal symptoms depends on the dose, duration of treatment and speed of dose reduction.

Mirtazapine has a relatively short half-life of 20 to 40 hours, which means withdrawal symptoms can begin within 1 to 3 days of the last dose or a significant dose reduction.

Typical timeline:

• Days 1 to 3: initial symptoms may appear, often starting with dizziness, irritability and sleep disturbance
• Days 3 to 7: symptoms often peak during this period. This is typically the most uncomfortable phase
• Weeks 2 to 4: most symptoms gradually improve. Physical symptoms tend to resolve before psychological ones
• Weeks 4 to 8: the majority of patients are symptom-free by this point when following a gradual taper

Prolonged withdrawal:

A minority of patients experience withdrawal symptoms lasting several months or, rarely, longer.

This is sometimes called "protracted withdrawal syndrome" and can include persistent low mood, anxiety and sleep disturbance.

NICE acknowledges that antidepressant withdrawal can be prolonged in some individuals and recommends supportive management.

Factors that influence duration:

• Length of treatment (longer courses tend to produce longer withdrawals)
• Speed of dose reduction (faster tapers produce more symptoms)
• Individual sensitivity
• Whether other changes (e.g. life stressors) coincide with the withdrawal

A gradual dose reduction is the cornerstone of safe mirtazapine withdrawal. The BNF and NICE both recommend tapering rather than abrupt cessation.

General tapering principles:

• Reduce gradually over at least 4 weeks for patients who have been on mirtazapine for a moderate duration
• Consider slower tapers (over several months) for patients on long-term treatment or those with previous withdrawal difficulties
• Make smaller reductions as you approach the lower doses, because the pharmacological impact of a dose reduction is proportionally greater at lower doses

Example tapering schedule (from 30 mg):

• Weeks 1 to 2: reduce to 22.5 mg (three-quarters of a 30 mg tablet, or use the oral solution for precision)
• Weeks 3 to 4: reduce to 15 mg
• Weeks 5 to 6: reduce to 7.5 mg (half of a 15 mg tablet)
• Weeks 7 to 8: reduce to 3.75 mg (quarter of a 15 mg tablet) or use oral solution
• Week 9: stop

Practical tips:

• Mirtazapine oral solution allows precise dose adjustments that are not possible with tablets alone
• If symptoms emerge at any stage, pause the taper and hold at the current dose until they settle
• Keep a symptom diary to track your progress
• Stay in regular contact with your GP throughout

NICE guidance:

NICE recommends that dose reductions should be informed by the patient's experience. If withdrawal is difficult, the taper should be slowed, and psychological support (such as CBT) may be helpful.

While tapering gradually is the most effective way to minimise withdrawal, additional strategies can help manage symptoms that do occur.

For insomnia:

• Practise good sleep hygiene: regular bedtime, cool dark room, no screens before bed
• Consider short-term use of a non-habit-forming sleep aid if approved by your GP
• Relaxation techniques such as progressive muscle relaxation or guided meditation

For anxiety and agitation:

• Breathing exercises and mindfulness can be genuinely helpful
• Gentle physical activity such as walking or yoga
• Avoid caffeine and stimulants, which may worsen anxiety
• Talk to friends, family or a counsellor about how you are feeling

For dizziness and physical symptoms:

• Stay well hydrated
• Avoid sudden movements, especially when standing up
• Eat regular, balanced meals
• Rest when needed but try to maintain some level of activity

For mood disturbance:

• Remember that withdrawal-related mood changes are temporary
• If low mood persists beyond 4 to 6 weeks after completing the taper, this may indicate relapse rather than withdrawal, and you should see your GP

When to seek help:

• If symptoms are severe or debilitating
• If you are having thoughts of self-harm
• If symptoms worsen rather than improve over time
• If you are unable to function at work or home

Your GP can adjust your tapering plan or provide additional support. Some patients benefit from referral to a psychiatrist for complex withdrawal management.