A person with clasped hands sits opposite another with a clipboard.

The number of prescriptions written for antidepressants in wealthy countries has doubled in the past 20 years. This increase is mostly due to people staying on antidepressants for a long time. There are now many people who have been on these drugs for several years and feel fairly well, but are unsure whether they still benefit from taking them.

Many people who have had depression continue to take antidepressants for years for fear that if they stop, they might have a relapse. Most studies of antidepressants and relapse have been done in people taking the medication for less than eight months. We wanted to know whether antidepressant treatment was still effective when people have been taking the pills for several years.

Our study, published in the New England Journal of Medicine, found that remaining on antidepressants long-term reduced the risk of a relapse, but many people were able to come off them safely.

Our study recruited 478 people who had been receiving long-term antidepressant treatment, 70% of whom had been taking antidepressants for more than three years. All the patients had a history of at least two episodes of depression, had been taking their antidepressants for a minimum of nine months, and felt well enough to consider stopping the pills.

All patients, from 150 GP surgeries in England, were interviewed by a researcher, and we excluded those who had symptoms of depression that met the criteria for a clinical diagnosis. We recruited people who were taking the most commonly prescribed antidepressants – sertraline, citalopram and fluoxetine. These are all selective serotonin reuptake inhibitors (SSRIs) that increase serotonin levels in the brain. We also included mirtazapine, a newer antidepressant that has been increasing in use in the UK.

We randomly allocated people to one of two groups: half of the study participants stopped taking their antidepressant medication and half continued. The group who stopped their medication were given reduced doses of their antidepressants for up to two months until they were on placebo only. The other group continued with the same dose of the antidepressant they were already receiving.

Neither researchers nor patients knew which group people were allocated to. This type of “double-blind study” helps to reduce bias. After the study started, we collected data from participants at intervals of six, 12, 26, 39 and 52 weeks after they started the trial.

Over the following year, 56% of people who stopped taking their antidepressants experienced a relapse, compared with 39% of people who kept taking them. So, remaining on antidepressants is appropriate for many people receiving long-term treatment from their GP. We didn’t find any evidence that the antidepressants in our study had serious side-effects.

Remaining on antidepressants did not guarantee wellbeing in our study – 39% of people who continued with their regular dose had a relapse within a year. The decision to remain on long-term treatment is offset by any potential side-effects and many people prefer not to take medication for many years.

No relapse in 44% of participants

In our study, many people were able to come off their antidepressants safely without a relapse. In the group who stopped their antidepressants, 44% did not relapse after a full year. Even among those who did relapse after stopping, only half chose to return to an antidepressant prescribed by their GP.

Many patients might decide to stop their antidepressants, in consultation with their doctor, knowing there might be a risk of relapse. If people who want to discontinue their antidepressants are regularly monitored by their GP, it may be possible to prevent relapses with different treatments, such as talk therapy. For example, studies have shown that mindfulness based cognitive therapy is effective at preventing relapse.

Alternatives to antidepressants include talk therapy.

There has been uncertainty about the extent to which people experience withdrawal symptoms after they stop taking antidepressants. In our study, people who stopped their antidepressants after reducing the dose over two months were more likely to experience withdrawal symptoms, such as irritability and difficulty in concentrating, than those who continued treatment. Yet, by the end of the study, a year later, 59% of the discontinuation group were not taking antidepressants.

Our study only provides information about the average probability of relapse. We do not yet know why some people are able to come off their antidepressants and some cannot. Further research may help us to predict who can stop antidepressants safely.

Our study provides an estimate of the risk of relapse if someone carries on with long-term antidepressants or decides to stop them. These findings will help doctors and patients to make an informed decision together on whether or not to stop long-term antidepressant treatment.

The Conversation

Glyn Lewis receives funding from NIHR. He has received income from Fortitude Law in relation to litigation concerning antidepressants.

Gemma Lewis does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.