Drug Class Guide
SSRIs (Selective Serotonin Reuptake Inhibitors)
The most commonly prescribed antidepressants, used first for depression and for most anxiety disorders.
How SSRIs Work
SSRIs slow the reabsorption of serotonin, a chemical messenger between nerve cells, leaving more of it available. The full effect on mood and anxiety builds gradually, usually over four to six weeks, even though side effects can appear in the first days.
What SSRIs Treat
SSRIs in Our Medication Guide
- SertralineZoloftApproved for depression, panic disorder, PTSD, OCD, social anxiety and PMDD.
- EscitalopramLexaproApproved for depression and generalized anxiety; few drug interactions.
- FluoxetineProzac, SarafemVery long-acting, so a missed dose matters less; also approved for bulimia.
- ParoxetinePaxilMore sedating, with more withdrawal symptoms if stopped abruptly; generally avoided in pregnancy.
Common Side Effects
Nausea, headache, changes in sleep and sexual side effects are the most common. Early side effects often fade within a few weeks; sexual side effects are more likely to persist. Some people feel restless or more anxious at first, which is why doses usually start low.
Important Cautions
- All antidepressants carry an FDA boxed warning about suicidal thoughts in children, teens and young adults under 25, especially in the first months.
- Combining SSRIs with other serotonin-raising drugs, such as tramadol, can cause serotonin syndrome.
- Bleeding risk rises when SSRIs are combined with NSAIDs or blood thinners.
- Older adults are checked for low sodium after starting.
Common Questions About SSRIs
How long does an SSRI take to work?
Sleep, energy and appetite may improve within one to two weeks, but the full effect on mood and anxiety usually takes four to six weeks, sometimes longer. If there is little change after that, your doctor may adjust the dose or try another medicine.
Is it safe to stop an SSRI suddenly?
Stopping abruptly can cause discontinuation symptoms such as dizziness, irritability, flu-like feelings and electric-shock sensations, and depression can return. These are more common with short-acting SSRIs such as paroxetine. Your doctor can taper the dose gradually.
What is the difference between an SSRI and an SNRI?
SSRIs raise serotonin; SNRIs raise both serotonin and norepinephrine. They work about equally well for depression and anxiety. SNRIs such as duloxetine are also used for some kinds of chronic pain but can raise blood pressure.
This guide is general information, not a substitute for advice about your own medicines. Do not start, stop or switch a medication without talking with your doctor. Questions about a prescription? Our internal medicine team can help.
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Trusted Resources for SSRIs
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