Class Explorer · Psychiatry
Atypical antidepressants
Antidepressants that do not fit the SSRI or SNRI template. Their differences are the reason they exist: each one is chosen for a side effect somebody wants.
Members
MirtazapineSedation and appetite as the point, not the side effect.BupropionActivating, weight-neutral, no sexual side effects, and it lowers the seizure threshold.
Also in this class: Trazodone · Vortioxetine. Full pages arrive as the library grows.
Compare the members
Mirtazapine
- Signature effect
- Sedating, appetite-stimulating
- Weight
- Gain
- Sexual dysfunction
- Minimal
Bupropion
- Signature effect
- Activating
- Weight
- Neutral or loss
- Sexual dysfunction
- Minimal
Shared across the class
- Indications
- Major depressive disorder
- Adverse effects
- Agent-specific; the class shares almost nothing
- Contraindications
- Concurrent or recent MAO inhibitor
- Monitoring
- Mood and suicidality, especially in the first weeks and in the young · Weight, in both directions · Sleep
What makes each agent different
- Mirtazapine sedates and increases appetite. In a depressed older adult who is not sleeping and is losing weight, those are not side effects, they are the indication.
- Bupropion is activating, weight-neutral to weight-reducing, and does not cause sexual dysfunction, which is why it rescues patients who abandoned an SSRI for that reason. It lowers the seizure threshold and is avoided in eating disorders and untreated epilepsy.
- Neither is a first-line agent by default; both are first-line for the right person.
Mirtazapine is more sedating at 15 mg than at 45 mg: the antihistamine effect saturates while the noradrenergic effect keeps climbing. Increasing the dose for insomnia is backwards.
Bupropion is also a smoking-cessation drug under another name, which means double-prescribing is a real and checkable error.
Last reviewed 2026-08-16 · Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed.