The Complete Antidepressant List: SSRIs, SNRIs, Atypicals, and What Each Treats

If you are researching antidepressants, you have probably noticed that there are more options than you expected, with names that seem interchangeable and uses that overlap.

That complexity reflects something real. Depression is not a single biological process, and the medications developed to treat it target different neurotransmitter systems, produce different side effect profiles, and are more or less appropriate depending on what a patient’s specific clinical picture looks like.

This guide organizes the major classes by mechanism, explains what each one treats, and covers the side effect profile honestly. The goal is to give you a frame for understanding what your prescriber is deciding when they recommend a particular medication.

What This Page Covers

• SSRIs: the most commonly prescribed class
• SNRIs: when a broader mechanism helps
• Atypical antidepressants: different targets, different advantages
• TCAs: effective but older, with heavier side effect burdens
• MAOIs: the last-resort class with the most restrictions
• Newer agents: esketamine, zuranolone, and what comes next

SSRIs: The Default Starting Point

Approximately 11.4% of American adults take antidepressants, according to 2023 data published by the Centers for Disease Control and Prevention, and SSRIs account for the largest share of those prescriptions. Selective serotonin reuptake inhibitors work by blocking the serotonin transporter, preventing serotonin from being reabsorbed into the presynaptic neuron after release. The result is increased serotonin availability in the synapse.

This mechanism does not mean that depression is simply “low serotonin.” The biology is more complex, and SSRIs produce their effects through downstream changes in receptor sensitivity, neuroplasticity, and gene expression over weeks. The 2 to 6 week onset period reflects that complexity.

The commonly prescribed SSRIs:

Sertraline (Zoloft) is one of the most versatile medications in the class, with FDA approval for major depressive disorder, panic disorder, OCD, PTSD, social anxiety disorder, and premenstrual dysphoric disorder. It is a common first prescription because of its broad indication profile and well-documented tolerability.

Escitalopram (Lexapro) is the most selective of the SSRIs, with a relatively clean drug-interaction profile that makes it useful for patients on other medications. It has FDA approval for major depressive disorder and generalized anxiety disorder in adults.

Fluoxetine (Prozac) is notable for its unusually long half-life of 4 to 6 days for the parent compound and 4 to 16 days for its active metabolite. That long half-life means missing a dose is less clinically disruptive than with other SSRIs. It has FDA approval for OCD, bulimia nervosa, and panic disorder alongside depression.

Paroxetine (Paxil) is the most sedating SSRI, useful for patients with prominent anxiety or sleep disturbance. It carries the highest rate of discontinuation symptoms among SSRIs, due to its short half-life. Tapering is important.

Citalopram (Celexa) has FDA approval for depression and a dosing cap of 40 mg due to QT interval prolongation risk at higher doses.

Common SSRI Side Effects

Initial: nausea, headache, insomnia, jitteriness, diarrhea. Most resolve within 2 to 6 weeks. Persistent: sexual dysfunction in 30 to 40% of patients. Weight gain is mild with most SSRIs but more pronounced with paroxetine. Discontinuation syndrome if stopped abruptly, particularly with paroxetine.

SNRIs: Adding Norepinephrine to the Mechanism

Serotonin-norepinephrine reuptake inhibitors block the reuptake of both serotonin and norepinephrine. The added norepinephrine component provides broader neurotransmitter modulation that is clinically useful in specific populations.

Venlafaxine (Effexor XR) is widely prescribed for depression and anxiety. It has FDA approval for generalized anxiety disorder, social anxiety disorder, and panic disorder. Dose-dependent blood pressure elevation is a consideration at higher doses.

Duloxetine (Cymbalta) has FDA approval for major depressive disorder, generalized anxiety disorder, fibromyalgia, diabetic peripheral neuropathy, and chronic musculoskeletal pain. For patients with co-occurring depression and chronic pain conditions, duloxetine’s dual indication is a meaningful clinical advantage.

Desvenlafaxine (Pristiq) is the active metabolite of venlafaxine, requiring less hepatic metabolism and making it a consideration for patients with liver concerns.

Levomilnacipran (Fetzima) has a relatively stronger norepinephrine effect compared to other SNRIs, which may be advantageous for depression with fatigue or low motivation.

Common SNRI Side Effects

Similar to SSRIs: nausea, headache, sexual dysfunction. Additional: blood pressure elevation (dose-dependent, particularly with venlafaxine), increased heart rate. Discontinuation syndrome is prominent with venlafaxine due to its short half-life and should be managed with gradual tapering.

Atypical Antidepressants: Different Mechanisms, Different Profiles

“Atypical” indicates a medication that does not fit neatly into the SSRI or SNRI categories. This class is clinically heterogeneous: its members work through different mechanisms and serve different patient profiles.

Bupropion (Wellbutrin) inhibits dopamine and norepinephrine reuptake with minimal serotonergic activity. This distinct mechanism means bupropion does not produce the sexual dysfunction common with SSRIs and SNRIs. It is also weight-neutral to mildly weight-reducing. It has FDA approval for depression and smoking cessation (as Zyban). It carries a dose-dependent risk of lowering the seizure threshold and is contraindicated in patients with seizure disorders or active eating disorders.

Mirtazapine (Remeron) works through alpha-2 adrenergic receptor blockade and histamine H1 receptor antagonism. Its sedating, appetite-stimulating properties make it particularly useful for patients with depression accompanied by severe insomnia and significant appetite suppression or weight loss. The weight gain and sedation that are mirtazapine’s most common side effects can actually be clinical assets for the right patient.

Trazodone has FDA approval for depression but is most commonly prescribed off-label in low doses for insomnia related to depression. At low doses (25 to 100 mg at bedtime), it improves sleep without dependency risk.

Vortioxetine (Trintellix) combines SSRI-like serotonin reuptake inhibition with direct activity at multiple serotonin receptor subtypes. Clinical trials have suggested cognitive benefits beyond what is typical with SSRIs, particularly in processing speed and executive function.

Vilazodone (Viibryd) combines serotonin reuptake inhibition with partial agonism at 5-HT1A receptors, offering both antidepressant and anxiolytic effects through a single mechanism.

TCAs: Effective, But With Heavier Side Effect Burdens

Tricyclic antidepressants were among the first pharmacological treatments for depression, introduced in the 1950s. They remain effective: for severe melancholic depression, some guidelines suggest TCAs may have advantages over SSRIs. But their side effect profile limits their use as first-line agents.

TCAs block serotonin and norepinephrine reuptake but also affect muscarinic, histamine H1, and alpha-adrenergic receptors, producing a broad range of additional effects. Common side effects include dry mouth, constipation, blurred vision, urinary retention, dizziness, tachycardia, and memory impairment. Overdose risk is significantly higher than with SSRIs.

Most-used TCAs include amitriptyline (Elavil), nortriptyline (Pamelor), imipramine (Tofranil), and clomipramine (Anafranil, with specific FDA approval for OCD). TCAs are also used off-label for chronic pain, migraine prevention, and neuropathic pain.

MAOIs: Reserved for When Other Treatments Fail

Monoamine oxidase inhibitors increase levels of serotonin, norepinephrine, and dopamine by blocking the enzyme that breaks them down. They are among the oldest antidepressants and remain among the most effective, particularly for atypical depression features.

The clinical limitation is that MAOIs interact dangerously with tyramine-containing foods (aged cheeses, cured meats, fermented foods) and with numerous medications, including SSRIs, SNRIs, opioids, and stimulants. These interactions can cause hypertensive crisis or serotonin syndrome. They require significant dietary discipline and careful medication management.

Phenelzine (Nardil) and tranylcypromine (Parnate) are the traditional oral MAOIs. Selegiline (Emsam) is available as a transdermal patch; at lower doses, it can be used with fewer dietary restrictions. MAOIs are generally reserved for patients who have not responded to multiple other antidepressant trials.

Newer Agents: Rapid Action and Novel Mechanisms

Esketamine (Spravato), approved by the FDA for treatment-resistant depression and for major depressive disorder with acute suicidal ideation, works as an NMDA receptor antagonist, targeting glutamate rather than monoamine neurotransmission. Its onset of action is measured in hours rather than weeks. It is administered in a certified healthcare setting due to monitoring requirements.

Zuranolone (Zurzuvae), approved in 2024, is the first oral medication specifically designed for postpartum depression and also approved for major depressive disorder. It targets GABA-A receptors through a neuroactive steroid mechanism, producing rapid effects over a 14-day course.

These newer agents are not typically prescribed before SSRIs, SNRIs, and atypical antidepressants have been tried. Their value is in extending the range of options for patients who have not responded to conventional treatment.

How Prescribers Choose

No antidepressant will work for every patient. Selection involves weighing efficacy, tolerability, the patient’s specific symptom profile, comorbid conditions, other medications, prior treatment history, and patient preferences.

Factors a prescriber considers include: the patient’s particular symptoms, possible side effects, whether the medication worked for a close relative, interactions with other medications, pregnancy or breastfeeding status, other health conditions, and cost and insurance coverage. A patient who has had a close relative respond well to a specific antidepressant has pharmacogenomic signal worth considering.

The best predictor of staying on an antidepressant long enough for it to work is tolerating its side effects. A medication that works pharmacologically but produces intolerable sexual dysfunction, weight gain, or sedation is not a sustainable treatment for most people. That conversation should happen before the prescription is written.

How SiggyMD Approaches This Decision

SiggyMD’s clinical intake gathers the information that drives antidepressant selection: current symptoms, symptom history, prior medication trials, comorbid conditions, and what matters most to the patient in terms of tolerability. A licensed prescriber reviews all of that before any treatment plan is approved.

After treatment starts, daily check-ins track how the medication is working and what side effects are present. That data reaches the prescriber continuously, not at the next quarterly appointment.

“My job is to match the right medication to the right patient and then stay close enough to adjust when something needs to change,” says Daniel Montville, MD, Psychiatrist, of the SiggyMD clinical team. “I can only do that if I know what is happening between visits. The check-in data is how I know.”

What Members Are Saying

BL

B.L., 33

Major Depressive Disorder

“I went through three SSRIs over four years. Each one worked for a while and then stopped. No one ever suggested a different class until I asked specifically. When I switched to bupropion, the sexual side effects that had bothered me for years disappeared. I wish someone had presented the full picture earlier.”

RC

R.C., 47

Depression with Chronic Pain

“My prescriber chose duloxetine because I had both depression and nerve pain from a back injury. The same medication was addressing both. That felt like real precision. Not just treating one thing at a time.”

Member stories reflect real experiences. Names and identifying details have been changed to protect privacy. Results vary. SiggyMD is currently invite-only.

Bottom Line

There are more antidepressant options than most patients realize, and the differences between them are clinically meaningful. SSRIs are the standard starting point. SNRIs offer advantages for patients with co-occurring anxiety or pain. Atypicals like bupropion and mirtazapine address side effect concerns or specific symptom patterns. TCAs and MAOIs remain options when first- and second-line agents have not worked. Newer mechanisms like esketamine are expanding what is possible for treatment-resistant cases.

The medication that is right for you reflects your specific clinical picture. That picture deserves a real conversation with a prescriber who understands it.

If you would like to understand more about how prescribing decisions work, you can read about how doctors decide when a first-line antidepressant is not working or start your anonymous intake with SiggyMD to get a clinician-reviewed treatment plan that fits your situation.

Sources

1. Mayo Clinic. Antidepressants: Selecting one that’s right for you. Accessed June 2026.

2. Cleveland Clinic. Antidepressants: What They Are, Uses, Side Effects and Types. Last updated August 2025.

3. Gárate Pérez MF, et al. Depressive disorders: systematic review of approved psychiatric medications (2009-April 2025) and pipeline phase 3 medications. PMC. 2025.

4. LifeStance Health. 2025 New Antidepressant Medications.

5. Discover Recovery. What Are the Top 10 Depression Medications? Citing CDC data, April 2025.

6. RxList. The Comprehensive List of Antidepressant Medications and Drug Class.

7. Nawaz A, et al. Advances in Antidepressant Therapy: Comparing the Efficacy of SSRIs, SNRIs, and Novel Agents. Cureus. 2024;16:e76318.