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SSRI comparison.

Published July 10, 2026 · Last reviewed July 14, 2026 by Shariq Refai, MD, MBA, FAPA

A factual reference to the six SSRIs commonly prescribed in the US, for understanding a prescription, not for adjusting one.

Medically reviewed by Shariq Refai, MD, MBA · Last reviewed July 10, 2026

Before you use this reference, please read.

This is educational reference, not medical advice. Don't start, stop, switch, or adjust any medication based on what you read here. Medication decisions depend on your full clinical picture, other medications, medical conditions, allergies, pregnancy status, family history, and how you actually respond, none of which a reference page can know. Those decisions belong to a licensed prescriber who has evaluated you.

Doses shown are FDA-labeled starting ranges for adults. They're typical, not universal. Real-world starting doses vary based on the reason for treatment, age, medical conditions, other medications, sensitivity, and prescriber judgment. Don't use them as a target for yourself.

Stopping an SSRI suddenly can cause discontinuation symptoms. If you're on one and want to come off, talk with your prescriber about a taper. Don't stop cold on your own.

If you're in crisis, call or text 988 in the US to reach the Suicide and Crisis Lifeline, available 24 hours a day. Call 911 if someone is in immediate danger.

Quick answer

SSRIs, selective serotonin reuptake inhibitors, are a class of medications that increase serotonin availability in the brain by blocking its reabsorption at the synapse. Six are commonly prescribed in the US: sertraline (Zoloft), fluoxetine (Prozac), escitalopram (Lexapro), citalopram (Celexa), paroxetine (Paxil), and fluvoxamine (Luvox). Each is FDA-approved for one or more mental-health conditions, most commonly major depressive disorder and anxiety disorders. They differ in how long they stay in the body, which conditions they're formally approved for, and their side-effect profiles, but their core mechanism is the same, and clinical outcomes among the class are broadly similar.

What SSRIs are.

SSRIs work by blocking the serotonin transporter (SERT) on presynaptic neurons, which reduces reuptake of serotonin from the synaptic cleft and increases its availability. The full clinical effect for depression and anxiety takes weeks to develop, the pharmacologic effect is immediate, but the downstream changes in receptor sensitivity, gene expression, and neural circuits take time. Most patients notice meaningful improvement by 4 to 6 weeks; some notice partial benefit earlier, and some need longer. If it helps to picture it, see how SSRIs work at the synapse in PsychiatryRx's interactive, psychiatrist-reviewed guide.

SSRIs are first-line pharmacologic treatment for major depressive disorder, generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, and social anxiety disorder in most clinical practice guidelines (American Psychiatric Association; NICE). Which specific SSRI is chosen depends on the condition being treated, the patient's history, side-effect profile, drug interactions, cost and coverage, and prescriber judgment.

The comparison table.

Everything below is drawn from FDA prescribing information for each drug. Half-lives, doses, and indications are simplified for reference. The full labeling is authoritative, links are provided in the sources section.

Medication FDA-approved uses (adults) Typical adult starting dose Half-life Notable considerations
Sertraline
Zoloft		 MDD, OCD, panic disorder, PTSD, social anxiety disorder, PMDD 25 to 50 mg once daily ~26 hours (parent drug) Broad range of FDA-approved uses. Commonly used first-line. GI side effects (nausea, loose stools) common early; usually improve.
Fluoxetine
Prozac		 MDD, OCD, panic disorder, bulimia nervosa, PMDD; combination use in bipolar depression and treatment-resistant depression 10 to 20 mg once daily 1 to 4 days (parent); 7 to 15 days (active metabolite norfluoxetine) Very long half-life, self-tapering, less discontinuation syndrome, but slower to wash out for interactions or switches. Activating for some.
Escitalopram
Lexapro		 MDD, generalized anxiety disorder 10 mg once daily 27 to 32 hours Generally well-tolerated. Fewer drug interactions than most SSRIs. Commonly first-line for GAD.
Citalopram
Celexa		 MDD 20 mg once daily ~35 hours FDA maximum dose is 40 mg/day (20 mg/day for adults > 60 or CYP2C19 poor metabolizers) due to dose-dependent QT-interval prolongation. Check with prescriber if on other QT-prolonging medications.
Paroxetine
Paxil, Paxil CR		 MDD, OCD, panic disorder, PTSD, social anxiety disorder, GAD 10 to 20 mg once daily (immediate release) ~21 hours Broadest anxiety-disorder coverage. More anticholinergic effects and weight gain than others in the class. Notable discontinuation syndrome if stopped abruptly, taper slowly. Category-D,style pregnancy risk historically; discuss with prescriber if pregnancy is possible.
Fluvoxamine
Luvox		 OCD (adults and pediatric); social anxiety disorder in adults 50 mg at bedtime, titrated ~15 hours Primarily used for OCD. Strong CYP1A2 and CYP2C19 inhibitor, many drug interactions. Sedating for some, useful when insomnia is prominent.

What SSRIs share as a class.

Common early side effects (usually improve within 1 to 2 weeks): nausea, headache, mild GI upset, jitteriness or restlessness, sleep changes (insomnia or sedation), sweating, decreased appetite.

Common persistent side effects: sexual dysfunction (reduced libido, delayed orgasm, erectile difficulty) affects a substantial minority of patients across the class. Weight change is variable, some patients gain, some don't. Emotional blunting is reported by a subset of patients.

Warnings that apply across the class:

  • Increased risk of suicidal thinking in children, adolescents, and young adults up to age 24 during initial treatment. All SSRIs carry an FDA boxed warning about this. Close monitoring in the first weeks of treatment matters, especially for younger patients.
  • Serotonin syndrome, a potentially serious reaction from too much serotonergic activity. Risk rises when SSRIs are combined with other serotonergic medications (other antidepressants, triptans, tramadol, linezolid, methylene blue, MDMA, St. John's wort, and others). Symptoms include agitation, confusion, rapid heart rate, high blood pressure, dilated pupils, muscle rigidity, twitching, sweating, shivering, diarrhea, and in severe cases seizures and high fever. Requires urgent medical evaluation.
  • MAOIs are contraindicated with SSRIs, a washout period of at least 14 days (5 weeks after fluoxetine because of its long half-life) is required before switching.
  • Discontinuation syndrome, stopping suddenly, especially for short-half-life SSRIs like paroxetine, can produce dizziness, "brain zaps," irritability, nausea, flu-like symptoms, and insomnia. Tapering under prescriber supervision minimizes this.
  • Bleeding risk is modestly increased, especially in combination with NSAIDs or anticoagulants.
  • Hyponatremia (low sodium) can occur, more commonly in older adults.
  • Pregnancy and lactation, SSRIs cross the placenta and are present in breast milk. Some (notably paroxetine) have raised more concern than others in early pregnancy. Decisions in pregnancy involve weighing untreated depression risks against medication risks and require a prescriber's judgment.

What to expect week by week (general pattern).

  • Days 1 to 14. Side effects most prominent, nausea, jitteriness, sleep changes, headaches. Meaningful mood or anxiety improvement isn't yet expected.
  • Weeks 2 to 4. Early side effects usually settle. Some patients notice early benefit, often energy, sleep, or appetite before mood itself.
  • Weeks 4 to 6. Fuller therapeutic effect emerges for most responders.
  • Weeks 8 to 12. If little to no benefit by this point, most prescribers reassess, dose adjustment, switching, or adding another treatment.

This is a general pattern, not a promise. Individual timelines vary.

What this reference isn't.

This page compares six medications. It isn't a recommendation to take any of them, and it doesn't compare them to non-medication options such as therapy, exercise, or watchful waiting. Whether an SSRI is the right choice for you, and if so, which one, at what dose, for how long, and in combination with what else, is a clinical judgment that depends on the whole picture of your health. It requires a licensed prescriber who has evaluated you.

Care-routing framework

When evaluation may help, care can look like one of five things.

If you're considering an SSRI, thinking about coming off one, or want to talk through side effects, this is the honest menu. Choose what fits your situation, your insurance, and your access. Full framework and disclosure on the editorial strategy page.

  1. Your primary care doctor.

    The entry point most people already have. Many PCPs prescribe SSRIs for anxiety and depression and can refer if a specialist is needed. Often the fastest first conversation.

  2. A therapist through Psychology Today or your insurance panel.

    Therapy alongside or instead of medication. Evidence-based approaches like CBT are widely available for anxiety and depression. Psychology Today's directory lets you filter by insurance and specialty.

  3. A psychiatrist for prescribing and complex care.

    The right fit for a complex medication history, treatment that isn't working, or when you want the prescriber to be a specialist. Wait times for in-network psychiatrists in the US are often long, sometimes months.

  4. shrinkMD, one telepsychiatry option.

    shrinkMD is the network's independent telepsychiatry practice, board-certified, currently accepting adult patients in a limited set of US states. Transparently one option among many, not a recommendation above other qualified clinicians.

  5. 988 for crisis. This is a different moment.

    If you're thinking about suicide, in acute crisis, or someone you love is in danger right now, this isn't a "find a psychiatrist" moment. Call or text 988 in the US. Call 911 if someone is in immediate danger.

Full disclosure. The Shrink Network is founded by Shariq Refai, MD, who also owns shrinkMD. This site takes no referral fee, no affiliate commission, and no revenue for care sent to shrinkMD or any other clinician named here. We name shrinkMD because it's transparently one option, not because we recommend it above other qualified clinicians.

Sources.

Related resources.

The chart compares the class. These pages go drug by drug and question by question.

How to cite this page

APA-style suggested citation:

Refai S. SSRI comparison: a reference to the six SSRIs commonly prescribed in the US. The Shrink Network Toolkit Library. Published July 10, 2026. Accessed [date]. https://shrinknetwork.com/toolkit/ssri-comparison/

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Educational reference, not medical advice. This page is general education about a class of medications. It isn't a diagnosis, not a prescription, and not a substitute for evaluation by a licensed clinician. Don't start, stop, or change any medication based on what you read here. Reading this page doesn't create a doctor,patient relationship. If you're in crisis, call or text 988 in the US.