Is trazodone a mood stabilizer or antidepressant? Understanding a Multifaceted Medication

October 10, 2025 •

2 min read

While widely known for its sedative properties at lower doses, a 2023 review in Annals of General Psychiatry highlights that trazodone is primarily an FDA-approved antidepressant for major depressive disorder. The answer to is trazodone a mood stabilizer or antidepressant? lies in understanding its unique, dose-dependent mechanism of action.

Quick Summary

Trazodone is an atypical antidepressant used for major depressive disorder. Its effects are dose-dependent, with lower doses providing sedation for insomnia and higher doses serving an antidepressant function. It is not classified as a mood stabilizer, though it is sometimes used adjunctively in bipolar disorder.

Key Points

Antidepressant, Not a Mood Stabilizer: Trazodone is classified as an atypical antidepressant (specifically a SARI) and is FDA-approved for major depressive disorder.
Dose-Dependent Effects: At lower doses, trazodone acts as a sedative for insomnia and anxiety, while higher doses are required for its antidepressant properties.
Different Mechanisms of Action: Unlike true mood stabilizers that prevent bipolar mood swings, trazodone works by modulating serotonin and blocking specific receptors to address depressive and anxiety symptoms.
Used as Adjunct for Bipolar Disorder: While not a primary mood stabilizer, it is sometimes used in conjunction with other medications to treat symptoms of bipolar depression or insomnia.
Common Side Effects: The most frequent side effects are drowsiness, dizziness, and dry mouth, with more serious risks like cardiac arrhythmia and priapism being rare.
Low Abuse Potential: Trazodone is not a controlled substance and has a low risk of addiction or misuse compared to other sedatives, though dependence can still occur.

What is Trazodone?

Trazodone is an atypical antidepressant belonging to the serotonin antagonist and reuptake inhibitor (SARI) class. It is FDA-approved for major depressive disorder (MDD) but is frequently used off-label for conditions like insomnia and anxiety due to its unique dose-dependent effects.

The Dose-Dependent Pharmacology of Trazodone

Trazodone's effects vary significantly with dosage.

Low-Dose Effects: For Insomnia and Anxiety

At lower doses (25mg-100mg), trazodone primarily acts as a sedative. This is mainly due to blocking serotonin 5-HT2A, histamine H1, and alpha-1 adrenergic receptors. This makes it useful for insomnia and anxiety, sometimes preferred over more habit-forming sleep aids.

High-Dose Effects: For Depression

Higher doses (150mg-600mg) are needed for antidepressant effects. At these doses, trazodone also blocks the serotonin transporter, increasing serotonin levels in the brain to alleviate depressive symptoms.

Why Trazodone is Not a Mood Stabilizer

Trazodone is an antidepressant and is not classified as a mood stabilizer. Mood stabilizers are used to prevent manic and severe depressive episodes in bipolar disorder, and using an antidepressant alone in bipolar disorder can risk triggering mania. However, trazodone may be used with a mood stabilizer as an adjunct treatment for bipolar depression or insomnia.

Trazodone vs. Mood Stabilizers: A Comparison

Here's a comparison highlighting key differences:


Feature	Trazodone	Mood Stabilizers (e.g., Lithium)
Primary Classification	Atypical Antidepressant (SARI)	Mood Stabilizer
Mechanism of Action	Inhibits serotonin reuptake and antagonizes various receptors in a dose-dependent manner.	Normalizes mood by affecting several neurotransmitter systems and modulating intracellular signaling.
Primary Indication	Major Depressive Disorder (FDA-approved).	Bipolar Disorder (FDA-approved).
Common Off-Label Uses	Insomnia, Anxiety, PTSD.	Treatment-resistant depression (adjunct), Schizoaffective disorder.
Dosage Strategy	Lower doses for sedation, higher doses for antidepressant effects.	Titrated to achieve a therapeutic blood concentration.
Effect on Mood	Reduces depressive symptoms and promotes sleep.	Prevents and manages both manic and depressive episodes.
Use in Bipolar	Used as an adjunct to stabilize mood and treat specific symptoms, never as monotherapy.	Primary treatment to stabilize mood and prevent cycling.

Potential Side Effects and Safety Profile

Side effects of trazodone vary with dosage. Common side effects include drowsiness, dizziness, dry mouth, headache, and blurred vision. More serious but rare effects include irregular heartbeat, low blood pressure upon standing, and priapism. Combining it with other serotonin-increasing drugs can lead to serotonin syndrome. Abrupt discontinuation can cause withdrawal symptoms like nausea and agitation, so tapering the dose is recommended.

Conclusion

Trazodone is classified as an antidepressant due to its primary action of modulating serotonin to treat major depressive disorder. While its sedative properties at lower doses are useful for insomnia and anxiety, it does not function as a mood stabilizer, which are medications specifically designed to prevent mood swings in bipolar disorder. Trazodone may be used as an adjunct in bipolar depression, but it remains an antidepressant. Patients should always consult a healthcare provider for appropriate treatment and to understand the differences between medication classes.

Frequently Asked Questions

No, trazodone is not a mood stabilizer. It is an antidepressant and is not typically used alone for bipolar disorder, as it can potentially trigger a manic episode. In some cases, it may be used as an adjunct to a primary mood stabilizer to treat bipolar depression or insomnia.

The primary difference lies in their function and mechanism. Trazodone is an antidepressant used to treat depressive symptoms by modulating serotonin, while a mood stabilizer is used to prevent the extreme highs and lows (mania and depression) of bipolar disorder.

Trazodone is prescribed for sleep due to its dose-dependent effects. At lower doses, its sedative properties take effect, which is why it's often used off-label to treat insomnia and anxiety.

Yes, trazodone is often used off-label to treat anxiety disorders, particularly when accompanied by sleep disturbances. Its calming, sedating effects can be beneficial, though its use for anxiety is not FDA-approved.

For depression, it typically takes 1 to 2 weeks for initial effects and up to 4 to 6 weeks to feel the full benefit of trazodone.

Abruptly stopping trazodone can cause withdrawal symptoms, such as nausea, agitation, headache, and confusion. A doctor will typically recommend a gradual reduction in dosage to minimize these effects.

No, trazodone is not a controlled substance because it does not have a high potential for abuse or dependence compared to other medications used for anxiety or sleep, like benzodiazepines.