What are SSRIs (Selective Serotonin Reuptake Inhibitors)?
SSRIs (selective serotonin reuptake inhibitors) are the most widely prescribed class of antidepressant medication, and include drugs such as escitalopram, sertraline, fluoxetine and others. They work by increasing the availability of serotonin, a neurotransmitter involved in mood, anxiety and sleep regulation, in the brain. SSRIs are considered first-line pharmacological treatment for most cases of depression and many anxiety disorders because of their established effectiveness and generally favourable side-effect profile compared with older antidepressant classes.
Common indications
- Major depressive disorder
- Generalized anxiety disorder
- Panic disorder
- Social anxiety disorder
- Obsessive-compulsive disorder (typically at higher doses than for depression)
- Post-traumatic stress disorder
- Premenstrual dysphoric disorder
Common side effects
- Nausea or stomach upset, most common in the first one to two weeks
- Headache
- Sleep changes — either drowsiness or, less commonly, difficulty sleeping
- Sexual side effects, including reduced libido or delayed orgasm
- Initial increase in anxiety or restlessness during the first days of treatment
- Dry mouth
- Changes in appetite or weight over longer-term use
Precautions and warnings
- Inform the prescriber of all other medications, including over-the-counter drugs and supplements, due to interaction risk (particularly with other serotonergic drugs)
- A small increase in suicidal thoughts can occur in some people, particularly younger patients, in the early weeks of treatment — closer monitoring is standard practice during this period
- Should generally not be combined with MAOIs due to serious interaction risk
- Use in pregnancy and breastfeeding requires individual risk-benefit discussion with a psychiatrist
- Alcohol can worsen side effects and is generally best minimised while establishing a new medication
How long does it take to work?
Some improvement in physical symptoms like sleep or appetite may appear within one to two weeks, but the core mood and anxiety benefits typically take four to six weeks to become clearly noticeable, and a full assessment of response is usually made at six to eight weeks. This gradual onset is normal and expected, not a sign the medication isn't working.
Stopping or changing this medication
SSRIs should not be stopped abruptly, particularly after more than a few weeks of use, since sudden discontinuation can cause a recognised discontinuation syndrome (dizziness, flu-like symptoms, irritability, electric-shock sensations, sleep disturbance). When it's time to stop, the dose is generally tapered gradually under medical supervision rather than stopped all at once.
When to seek urgent care
Seek urgent medical attention for a severe allergic reaction, signs of serotonin syndrome (agitation, high fever, rapid heartbeat, muscle rigidity, confusion — especially if another serotonergic drug has also been taken), or any new or worsening thoughts of self-harm or suicide, particularly in the first weeks of treatment or after a dose change.
Why treatment is individualized
Which specific SSRI, at what dose, and for how long is an individual decision made with a psychiatrist based on the specific condition, other medications, physical health, prior treatment response and personal preference. This page is general education, not a recommendation for what any specific person should take.
Frequently asked questions
Are SSRIs addictive?
No, SSRIs are not addictive in the way substances like benzodiazepines or opioids are — they don't produce craving or a need for increasing doses to get the same effect. However, stopping them abruptly after regular use can cause a discontinuation syndrome, which is why tapering under medical guidance is recommended.
Will an SSRI change my personality?
SSRIs are not intended to and generally don't change core personality. Some people describe feeling more emotionally 'blunted' or less intensely reactive at certain doses, which is a recognised side effect some people experience and can usually be addressed by adjusting the dose or switching medication if it's troublesome — this is worth discussing with your prescriber rather than assuming it's an unavoidable trade-off.
How long do SSRIs take to start working?
Some physical symptoms may improve within one to two weeks, but the core antidepressant or anti-anxiety effect typically takes four to six weeks to become clear, with full response assessed around six to eight weeks.
Can I drink alcohol while taking an SSRI?
It's generally advisable to minimise alcohol, since it can worsen side effects like drowsiness and may affect how well the medication works. Discuss your specific situation with your prescriber.
What happens if I miss a dose?
Missing an occasional dose is usually not dangerous, but consistent daily use is important for steady effect. If you're unsure what to do after a missed dose, or miss doses frequently, discuss this with your prescriber rather than doubling up without guidance.
Can SSRIs be taken long-term?
Yes, for some people, particularly those with recurrent or chronic depression or anxiety, longer-term treatment is appropriate and reviewed periodically. Others take an SSRI for a defined period alongside therapy and later taper off. This is an individual decision reviewed over time, not a fixed rule.
References
- National Institute for Health and Care Excellence (NICE). Depression in adults: treatment and management.
- Royal College of Psychiatrists. Antidepressants patient information.
- American Psychiatric Association. Practice Guideline for the Treatment of Patients with Major Depressive Disorder.
Have questions about your medication?
Book a consultation to discuss whether this or another treatment is right for your specific situation.