What you should know before starting antidepressants

How often do you take them, what are the side effects and when could you start to feel better?

If you’ve been struggling with feeling low constantly, you are not alone. More than 8.6 million people in England were prescribed an antidepressant in 2022-23 to treat their melancholy and the figures are rising. For those considering taking medication, read on.
Antidepressants are a group of medications used to treat conditions such as depression and anxiety. 
“Antidepressant is an umbrella term that includes several classes of drugs, but there are similarities in how they work,” says Carmine Pariante, professor of biological psychiatry and a spokesperson for the Royal College of Psychiatrists. 
The four main types of antidepressants are:
“All antidepressants work by changing the function of chemicals that brain cells use to communicate,” Prof Pariante explains. As a result, antidepressants reduce the hyper-activation of areas in the brain that are associated with sadness or anxiety and help to reduce negative thinking. 
Antidepressants may be prescribed to treat a range of conditions, most commonly depression, generalised anxiety disorder (GAD), and other mental health issues, explains Dr Punam Krishan, an NHS GP. They can also be used to manage certain pain conditions, particularly neuropathic and chronic pain, she adds. 
Antidepressants are designed to treat “persistent and impairing” symptoms, which last for many weeks or months and have a significant impact on your day-to-day life. “Every person is different, and doctors should make a holistic assessment of the duration and severity of someone’s symptoms, and the practical impact those symptoms are having on their life,“ says Prof Pariante. “Whether, and when, to start antidepressants should be a collaborative decision with the patient,” he says. 
“I always say to my patients that a pill isn’t going to be the thing that fixes the problem. It very much depends on how severe someone’s symptoms are, but really you want to get to the root cause of why they are struggling with their mental health,” Krishan adds. 
“An antidepressant should always be prescribed as part of a management plan, alongside a combination of other options,” she explains. These include talking therapies, such as cognitive behavioural therapy (CBT), and looking at lifestyle factors such as sleep, diet, exercise, and drug or alcohol use.
Like all medications, antidepressants come with a range of possible side effects, most commonly including:
However, most side effects should settle down within a few days or weeks, says Dr Krishan.
That said, different types of antidepressant do have slightly different side effects, which are outlined in detail in the tables below. 
It’s also important to note – as with any drug – that individuals will have different reactions and tolerance levels to different pills.
If you find that the side effects aren’t settling down, Krishan says, contact your GP. It may be that one particular antidepressant, or class of antidepressants, doesn’t agree with you. Your doctor will be able to recommend an alternative.
It’s also important to contact your GP if your mental health deteriorates after starting antidepressants. Any serious side effects should be reported to the Yellow Card scheme, a government programme that aims to make medicines and medical equipment safer.
“A lot of people don’t bother reporting side effects, but it’s really important because that’s how we gather data and learn more about drug profiles so we can improve them in future,” Dr Krishan says. 
“With SSRI antidepressants like citalopram and fluoxetine, we do sometimes see a worsening of anxiety or depression symptoms, or even thoughts of suicide, in the first few days. It’s rare, but it’s one of the things we do have to warn people about,” she says. 
Although uncommon, this side effect can be serious and is more likely in young people than in adults over 30, Pariante explains.
“If it does happen, you must call your GP immediately and let us know,” Dr Krishan adds. “We would then stop that medication and change to something different.”
All antidepressants are taken daily, and it’s important to be consistent, Pariante says. “If you miss one or two days though, there’s not going to be a big disruption to how they work. You might experience side effects like dizziness, nausea or insomnia, or you may not notice any difference at all,” he adds. 
Continue taking your medication as normal, and don’t take any extra doses to make up for those you missed.
Krishan recommends taking your medication at the same time each day, at whatever time suits you. Some antidepressants can make you feel sleepy, so if that’s the case, it may be a good idea to take them before bed.
Besides the initial side effects, you may be wondering how antidepressants will make you feel, and how long it will take for them to work.
“It’s important to manage expectations. I always tell patients it typically takes anywhere from two to four weeks to fully feel whether antidepressants have been effective. Some people can have an earlier response, but you need to give it at least a couple of weeks,” Krishan says.
Bethan Screen, 30, has been taking a low dose of sertraline for a year and a half, as well as attending talking therapy, having struggled with anxiety and depression for many years. “Initially I was drowsy after taking them, so I took them at night, which actually helped with the effects of anxiety on my sleep,” she recalls. 
“I also felt a bit nauseous and they gave me a dry mouth, but that went away after three weeks, which is when I started to feel better too. I know some people have worse side effects, so I was a bit worried before I started them, but it wasn’t too bad at all for me,” she adds. “I think there’s still a stigma around taking medication, but I’m so grateful for mine. It gave me the stability to be able to implement what I was learning in therapy.”
When starting antidepressants, your doctor should consider any other medications you take before deciding on the best option for you.
“There are lots of medications that could interact with antidepressants. We’d be particularly vigilant if you were on any medications for your heart, because we don’t want to affect your blood pressure or heart rate, or if you had problems with your liver or kidneys, because a lot of these medications are metabolised via the liver and kidneys,” Krishan says.
You should also check with your doctor if you’re taking any non-prescription medications, supplements or herbal remedies, as these may have an impact. Finally, Pariante strongly advises against any recreational drug use when taking antidepressants and recommends keeping alcohol consumption to safe social levels.
There are guidelines for prescribing antidepressants, which lay out the minimum and maximum recommended dose. Any changes to your dose should be made in consultation with your doctor. 
“We always start low and go slow. Ideally, you want to have somebody established on the lowest dose possible that’s effective for them,” Krishan says. If you feel there hasn’t been a significant improvement after a few weeks on your initial dose, your GP may suggest increasing it.
Similarly, if you reach a point where you feel that you want to stop or reduce your antidepressants, also known as ‘tapering’, your doctor will advise the safest way to gradually do this to minimise withdrawal symptoms.
This will vary from person to person. However, as a general rule, Pariante says that “within two to three months of taking antidepressants, usually people will start to feel ‘normal’ again. If this was your first episode of depression, I recommend continuing to take them for another six to nine months after that, to consolidate the improvement.”
In the meantime, he adds, “You may have changed things about your work, relationships, lifestyle or habits. Antidepressants shouldn’t be seen in isolation as a way of getting better, but as a way of allowing people to make changes that will have a long-term effect on their mental health.” 
Reducing your dose should then be done slowly, over around two months, to minimise withdrawal effects.
People with more severe or recurrent depression may need to be on antidepressants for the longer term. “It’s always a question of balancing the quality of life without the antidepressant versus the quality of life with the antidepressant,” Pariante says. 
“We do see people staying on them for five, 10 years or more. However, we would generally recommend reviewing this with your doctor if you’ve had a prolonged period of wellbeing over several years. It might then be worth trying to stop slowly,” he adds.
“Generally I find that my patients know when they’re ready,” Krishan says.
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