Antidepressant choices: types, side effects and how decisions are made

The NHS describes antidepressants as medicines mainly used for the symptoms of depression, and also for other conditions including obsessive compulsive disorder, post-traumatic stress disorder, generalised anxiety disorder, panic disorder, social anxiety, bulimia, phobias, fibromyalgia or nerve pain, migraine and bedwetting in children. It says it is thought they work by affecting chemicals in the brain called neurotransmitters, such as serotonin and noradrenaline, which are linked to mood and emotion.

The NHS says all types of antidepressant generally work as well as each other to treat symptoms of depression, but there are differences in who can take them and in side effects. Some people find a certain type works better for them or causes side effects that are easier to live with.

NICE guideline NG222 says not to routinely offer antidepressant medication as first-line treatment for less severe depression, and to offer it only if that is the person's informed preference. Its first-ranked options for less severe depression include guided self-help, which uses materials based on cognitive behavioural therapy, behavioural activation or problem-solving. The guideline also advises discussing preferences, previous treatment experience, and waiting times for therapy, and says people have a right to decline treatment.

The NHS says antidepressants are usually not recommended to treat depression in children and young people under 18, although sometimes they may be used along with another type of treatment. Most adults can take antidepressants. Some can be taken in pregnancy and some while breastfeeding, with a doctor weighing benefits and risks.

NICE advises that when offering medication a management plan is agreed with the person, covering the reasons for offering it, the choices if more than one antidepressant is suitable, how doses may be adjusted, and the benefits and harms. It specifically mentions asking which side effects someone would particularly like to avoid, such as weight gain, sedation or effects on sexual function, and what concerns they have about stopping.

Other factors include existing physical health problems, other medicines (the NHS warns that some antidepressants interact with NSAIDs, other antidepressants, alcohol, cannabis, ketamine and St John's wort), previous responses, and safety in overdose. NICE says that for someone at significant risk of suicide, toxicity in overdose should be taken into account and TCAs, except lofepramine, should not routinely be started. It also advises against prescribing or recommending St John's wort for depression because of uncertainty about doses and potentially serious interactions.

The NHS says many side effects ease after a couple of weeks, though some may continue. Common ones include feeling sick, dry mouth, headaches, dizziness or drowsiness, trouble sleeping, sweating, weight gain, stomach upset, agitation, and sexual problems such as low sex drive or difficulty reaching orgasm. The possible side effects depend on the type. Reports of suspected side effects can be made through the Yellow Card scheme.

The NHS says suicidal thoughts or an urge to self-harm are not common but can occur when starting a medicine, and that people aged 24 or under, or who have had such thoughts before, may be most at risk. Speak to your doctor straight away if this happens, and call 999 or go to A&E if you are in danger or do not feel you can keep yourself safe. NICE says people should be reviewed within about 2 weeks of starting, or after 1 week if aged 18 to 25 or if there is particular concern about suicide risk.

The NHS says it can take several weeks before symptoms improve, so it is important to continue, and that you will usually continue for at least 6 months after symptoms improve. NICE tells prescribers to explain that the effect is usually seen within 4 weeks if the medicine is going to work, and that treatment should be reviewed regularly. Review between 2 and 4 weeks after any treatment starts is recommended to see how it is working and monitor for side effects and suicidal ideas.

The NHS says not to stop an antidepressant suddenly or without talking to your doctor first. A plan to reduce gradually, usually over several weeks or months, can help with withdrawal symptoms. NICE says withdrawal symptoms do not affect everyone and vary in type and severity; they may include dizziness, electric-shock sensations, irritability, anxiety, sleep problems, sweating, nausea, palpitations, headaches and aching joints. It says they are often mild and settle within 1 to 2 weeks, but can be longer or occasionally severe.

NICE adds that some commonly used antidepressants, including paroxetine and venlafaxine, are more likely to cause withdrawal symptoms, so particular care is needed. If someone has withdrawal symptoms, they should be reassured that this is not a relapse, and for severe symptoms a prescriber may consider restarting the original dose and reducing more slowly.

Most antidepressants are started by a GP, with NHS talking therapies and community mental health teams for assessment and support. A private psychiatrist can offer a longer assessment and review of medicines when several have been tried. The NHS says a New Medicine Service from a pharmacist is available for adults starting a commonly used antidepressant for the first time. Whoever prescribes, ask about the review schedule, expected timescale, how to stop, and what to do if you feel worse.