Millions of people take antidepressants each day, but a major new review of the data brings up some concerns with how the drugs are currently prescribed. 

In fact, when taken over long periods for mild and moderate depression, antidepressants may be doing patients more harm than good, the review explains. That's not to say we shouldn't use antidepressants at all – in many instances, they save lives and work well.

But the authors of the new review, which appears in the British Medical Journal's Drug and Therapeutics Bulletin, suggest doctors should prescribe fewer antidepressants for shorter periods of time, and focus on people with severe depression. In other cases, the evidence is unclear on how effective the drugs really are – and whether the benefits outweigh the side effects.

"There continues to be considerable uncertainty about the benefits of antidepressant use in the short- and long-term, particularly in regard to the lack of a clinically significant difference between antidepressant and placebo treatment," explain the authors, psychiatrist Mark Horowitz from University College London and pharmacist Michael Wilcock from Royal Cornwall Hospital. 

"In light of this uncertain balance of benefits and harms, we should re-visit the widespread – and growing – prescription of antidepressants." One of the big issues highlighted by the review is that most clinical trials only look at the efficacy of the drugs over a six- to 12-week study period. In the real world, however, people have been prescribed antidepressants for years.

More worryingly, most studies don't look at outcomes that matter most to patients, such as quality of life – they only measure symptoms. "About a fifth of patients on SSRIs report sleepiness during the day, dry mouth, profuse sweating or weight gain," the review notes. "A quarter of patients report sexual dysfunction, and about one in 10 report restlessness, muscle spasms or twitching, nausea, constipation, diarrhea or dizziness."

A survey of self-rated side effects in long-term use was even more concerning: 71 percent reported emotional numbness, 70 percent said they felt 'foggy or detached', 66 percent said they experienced sexual difficulties and 63 percent reported drowsiness. Another potential problem flagged by the authors is that the long-term use of antidepressants often starts in childhood.

In reality, there's very little clinical evidence that antidepressants work effectively in teenagers and young adults. And yet, antidepressants are one of the most commonly used drugs by adolescent girls, and the number of 12 to 17-year-olds prescribed antidepressants is increasing rapidly in some countries.  Of course, this isn't the first paper to question the effectiveness of antidepressants. For years, there has been discussion over whether they offer benefits.

A 2017 meta-analysis on the most widely used type of antidepressants, SSRIs (selective serotonin reuptake inhibitors), found there was only a 2-point difference between people taking active drugs and a placebo when measuring their outcomes on the Hamilton Depression Rating Scale, which ranges from 0 to 52.

The UK's National Institute for Health and Care Excellence says a 3-point difference is needed to make a 'clinical difference' – but other studies say it should be at least a 7-point difference if a drug is to be deemed clinically important. Either way, many modern antidepressants fall short.

This latest review doesn't offer new data in terms of evidence – or lack there of – regarding the efficacy of antidepressants. But what it does is weigh any potential benefits up against the side effects and risks.

It comes on the back of new guidance from the UK Royal College of Psychiatrists on how to stop taking antidepressants in a tolerable way. It's not talked about often, but patients can experience withdrawals such as headaches, anxiety, insomnia, agitation, fatigue and diarrhea, particularly if they stop their treatment too quickly. 

"The recognition that withdrawal effects from antidepressants are more common, more long-lasting and more severe than previously recognised prompted the Royal College of Psychiatrists to issue a position paper, alerting prescribers to this issue, including the recommendation that patients be informed of this risk," note the authors.

Currently the best way we know of to stop taking antidepressants is to reduce the dose gradually. But "there is no guarantee that patients will avoid consequences such as long-lasting sexual side effects or persistent withdrawal symptoms even with a cautious taper," the researchers write.

They also flag that the currently available doses don't go low enough to help patients taper off gradually, something else that needs to be revisited as we think about how best to use antidepressants going forward.

This review definitely isn't any kind of final word over the use of antidepressants – there are lots of hard decisions ahead and more research needed. But there's mounting evidence that the way we currently use these common medications may not be the best, and the more honest conversations we have now, the better care we can offer people with mental health concerns in future. It also highlights the importance of potential new treatments, including ketamine and psilocybin.

"Increasing knowledge about the difficulty that some patients have in stopping antidepressants should lead to more cautious prescribing practice – with antidepressants given to fewer patients, for shorter periods of time," the authors conclude. The review has been published in the Drug and Therapeutics Bulletin.