Mental health: Stopping and restarting medicines

Last updated: Monday, April 29, 2024

Stopping psychiatric medicines

Psychiatric medicines may need to be stopped for a range of reasons such as no longer being indicated or due to side effects, for example. 

Most antidepressants have been reported to cause a ‘discontinuation syndrome’ when stopped abruptly or if a few doses are missed. However it is important to realise that many patients are not affected. Paroxetine, venlafaxine and other drugs with a short half-life and inactive metabolites seem particularly likely to cause the problem. In contrast drugs such as fluoxetine with long-acting active metabolites (norfluoxetine) rarely cause discontinuation effects. 

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Note that the term ‘withdrawal’ is often used by patients, but less preferred by some experts due to its association with substance misuse. 

Discontinuation symptoms usually appear within a few days of stopping therapy and they may be mild and self-limiting. However they can also be quite broad-ranging and patients may think that they are suffering a relapse of their depression. If no action is taken, discontinuation symptoms are likely to subside after several weeks. Gradual dose reduction rather than abrupt withdrawal helps to reduce the risk of discontinuation symptoms. 

For example, sudden discontinuation of paroxetine can cause dizziness, sensory disturbances (e.g. electric shock sensations), sleep disorders, agitation or anxiety, nausea, tremor, confusion, sweating, headache, diarrhoea, and palpitations. An extended discontinuation period with careful step down is likely to be required and use of the liquid formulation will make final dose reductions more practical and comfortable. Letting the patient control the timeframe and addressing their anxieties may make for a more successful discontinuation. 

Any antidepressant suspected of causing a serious side effect should be stopped immediately (e.g. arrhythmias). 

A discontinuation syndrome may also occur in neonates born to mothers who have been taking antidepressants close to delivery. 

Questions about stopping antipsychotics are less common, but the same principles of tapering apply, to avoid discontinuation symptoms and to help identify early signs of any relapse.


Restarting psychiatric medicines

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You might be asked about when and how to restart psychiatric medicines after a temporary discontinuation, such as if the patient has suffered a serious side effect, taken an overdose or been non-adherent. 

For some medicines, the product manufacturer gives specific advice in the SmPC (e.g. clozapine) but in most cases such guidance is lacking. In these situations, you will usually need to consider the clinical condition of the patient, the length of time the patient has been without therapy, and the side effect and pharmacokinetic profile of the medicine. A patient who has been without medication for more than a few days may need to be initiated on therapy again ‘from scratch’ such as with methadone where tolerance is lost within a few days. 

For example, you might be asked about a patient with schizophrenia who has forgotten to take their quetiapine for a week. Re-starting the patient on a dose similar to their old maintenance dose seven days ago risks side effects such as postural hypotension because the amount of drug left in their system will be low. However, if you treat the patient with the low doses usually used to initiate therapy it will take longer to control the patient’s symptoms. You will need to balance safety (side effects and ability to monitor patient) versus their clinical condition (severity of symptoms, dangers to themself and others). What you recommend should also take into account the level of support available to the patient (e.g. healthcare professionals, carers) and the patient’s views given that they will not be naive to the medicine.