Sertraline

Is sertraline safe?

For most adults, yes. Sertraline, sold as Zoloft in the US and Lustral in the UK, is a selective serotonin reuptake inhibitor (SSRI) and one of the most prescribed antidepressants in the world. It is far less dangerous in overdose than the older tricyclics it largely replaced, and it is not addictive.

It is not a trivial medicine, though. Side effects are common in the first weeks, it carries a boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary for suicidal thoughts in young people, and it interacts with a range of other drugs. We score it 72: good, with specific risks that are manageable with the right monitoring.

The boxed warning, in numbers

Since 2004 every antidepressant in the US has carried a boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary about suicidal thoughts and behaviour in children and teenagers, extended to young adults under 25 in 2007. It is based on pooled short-term trials of about 77,000 adults and more than 4,400 children. Compared with placebo, antidepressants led to:

Age	Change in suicidal thoughts or behaviour per 1,000 treated
Under 18	14 more
18 to 24	5 more
25 to 64	1 fewer
65 and over	6 fewer

No suicides occurred in the children's trials. The warning is about watching closely in the first months and after dose changes, not about avoiding treatment: depression itself is the biggest risk factor for suicide. Families should report new agitation, worsening mood or talk of self-harm to the prescriber straight away.

Side effects most people notice

In the Zoloft label's pooled trials, the most common effects were:

• nausea (26% vs 12% on placebo) and diarrhoea (20% vs 10%)
• insomnia (20% vs 13%), tremor and sweating
• sexual side effects, including ejaculation failure in 8% of men vs 1%, and lower libido

Stomach effects usually settle within a few weeks. Sexual side effects often persist and are a common reason people stop. They are worth raising with a doctor, as there are options.

Interactions to know about

The dangerous combination is with MAOI antidepressants, the antibiotic linezolid or intravenous methylene blue, which can cause serotonin syndromeSerotonin syndromeA reaction caused by too much serotonin in the body, usually from combining medicines that raise it. Symptoms range from shivering to high fever.More in the glossary: agitation, fever, sweating, muscle twitching and a fast heartbeat. The label contraindicates these and pimozide. Tramadol, triptans for migraine, other antidepressants, lithium and St John's wort also add serotonin effects. Our 5-HTP page covers the same risk with that supplement.

SSRIs reduce the ability of platelets to clump, so bleeding risk rises with ibuprofen, aspirin and warfarin. Older adults are also more prone to low blood sodium on SSRIs, which shows up as confusion, headache or unsteadiness.

Stopping sertraline

Sertraline is not habit-forming in the way alprazolam is. There is no high and no craving. But stopping abruptly can cause discontinuation symptoms: dizziness, electric-shock sensations, irritability, flu-like feelings and vivid dreams. For some people they last weeks. The label advises a gradual reduction, and current UK guidance recognises that some people need a slow taper over months. Plan any change with your prescriber.

Doses

The usual starting dose for depression is 50 mg once a day, and 25 mg for panic disorder, PTSD and social anxiety. Doctors raise it in steps no more often than weekly, up to a maximum of 200 mg a day. Overdose of sertraline alone is rarely fatal, but any overdose needs urgent assessment, especially if alcohol or other drugs are involved.

Who should be careful

Talk to your doctor or pharmacist before starting sertraline, or before adding anything new to it, if you:

• are under 25, or have had thoughts of suicide or self-harm
• have bipolar disorder or a past episode of mania, which an SSRI can trigger
• take a blood thinner, regular NSAIDs, tramadol, a triptan or another antidepressant
• are over 65, take diuretics or have had low sodium before
• have epilepsy, glaucoma or a heart rhythm problem
• are pregnant, planning a pregnancy or breastfeeding

How we scored it

Track record (92) and overdose marginOverdose marginHow far a normal dose is from a harmful one. A wide margin means an accidental extra dose is unlikely to cause serious harm.More in the glossary (82) are strong for a psychiatric medicine. Regulatory warnings (50) reflect the boxed warningBoxed warningThe strongest safety warning the US FDA puts on a medicine's label, printed inside a black border at the top.More in the glossary for under-25s, interactions (60) the serotonin and bleeding risks, and dependence (80) the discontinuation symptoms rather than addiction.