What Is Trazodone (Desyrel)? Uses, Side Effects & Warnings

Trazodone is a prescription antidepressant classified as a serotonin antagonist and reuptake inhibitor (SARI). It was first approved by the FDA in 1981 under the brand name Desyrel for the treatment of major depressive disorder. Today, however, the vast majority of trazodone prescriptions in the United States are written off-label — primarily for insomnia. It is available in immediate-release tablets (50 mg, 100 mg, 150 mg, and 300 mg strengths) and in an extended-release formulation (Oleptro, 150 mg and 300 mg).

What Trazodone Is Used For

The FDA-approved indication for trazodone is major depressive disorder (MDD). At the higher end of the therapeutic range used for depression, it produces meaningful antidepressant effects. However, its use for depression has been largely displaced by SSRIs and SNRIs, which tend to be better tolerated for that purpose.

Off-label, trazodone is one of the most commonly prescribed medications for insomnia. Because it causes significant sedation even at lower doses, physicians frequently prescribe it as a sleep aid. It is also used off-label for anxiety, post-traumatic stress disorder (PTSD) — particularly to reduce nightmares — and to manage agitation in patients with Alzheimer's disease.

How Trazodone Works

Trazodone has a complex, multi-receptor pharmacology. Its name — serotonin antagonist and reuptake inhibitor — captures two of its primary actions. It blocks the reuptake of serotonin (similar to SSRIs), increasing serotonin levels in the synapse. But it also antagonizes certain serotonin receptors (specifically 5-HT2A and 5-HT2C), which is thought to contribute to its antidepressant effects and may reduce the sexual side effects seen with pure reuptake inhibitors.

Its sedating effects are primarily explained by a third mechanism: potent blockade of histamine H1 receptors (antihistamine activity) and alpha-1 adrenergic receptors. It is these receptor-blocking properties — not serotonin reuptake inhibition — that make trazodone sedating, which is why its sleep effects kick in even at doses too low to produce meaningful antidepressant benefits.

Common Side Effects

• Drowsiness and sedation (the most common side effect; desired when used for sleep)
• Dizziness and lightheadedness, especially when standing up quickly (orthostatic hypotension)
• Dry mouth
• Blurred vision
• Headache
• Nausea (less common than with SSRIs, especially if taken with food)
• Next-day grogginess or "hangover" effect
• Constipation
• Weight changes (typically modest)

Important Warnings

Despite being an antidepressant, trazodone does not carry the dependence risks of benzodiazepines or "Z-drugs" (zolpidem, eszopiclone). It is not a controlled substance and does not cause the same pattern of physical dependence or rebound insomnia upon stopping. However, it should not be stopped abruptly at doses used for depression, as discontinuation symptoms (dizziness, anxiety, irritability) can occur.

Trazodone should be used with caution in people with known heart disease, as it can rarely cause cardiac arrhythmias. It is also not recommended in people with a history of priapism or who are taking medications that cause prolonged QT interval.

Key Drug Interactions

Combining trazodone with other serotonergic medications — including SSRIs, SNRIs, MAO inhibitors, tramadol, or St. John's Wort — raises the risk of serotonin syndrome, a potentially life-threatening condition characterized by agitation, rapid heart rate, high temperature, and muscle rigidity. MAO inhibitors (phenelzine, tranylcypromine) are contraindicated with trazodone; a washout period is required when switching between them.

Trazodone is metabolized by the CYP3A4 enzyme. Drugs that inhibit CYP3A4 (such as ketoconazole, ritonavir, and clarithromycin) can raise trazodone blood levels, increasing the risk of side effects. CYP3A4 inducers like rifampin and carbamazepine can reduce trazodone's effectiveness.

Alcohol amplifies trazodone's sedative effects and should be avoided during treatment.

Frequently Asked Questions

Is trazodone habit-forming?

Trazodone is not a controlled substance and does not carry the addiction or dependence risk associated with benzodiazepines or Z-drugs like zolpidem (Ambien). It does not cause the same tolerance, withdrawal seizures, or drug-seeking behavior. This is the primary reason it is preferred over benzodiazepines as a long-term sleep aid for many patients.

How long does it take for trazodone to work for sleep?

For insomnia, trazodone's sedating effects typically begin working within the first night or two of use. This contrasts with its antidepressant effects, which take 2–4 weeks to become apparent. Because of this quick onset for sleep, it is often used as a bridge while waiting for a primary antidepressant to take effect.

Why doesn't trazodone cause sexual side effects like SSRIs?

The sexual side effects of SSRIs — delayed orgasm, decreased libido, and erectile dysfunction — are largely attributed to excessive stimulation of 5-HT2A receptors secondary to increased serotonin levels. Trazodone actually blocks 5-HT2A receptors, which offsets this effect. In fact, at lower doses, trazodone has historically been associated with improved sexual function in some patients — though paradoxically, this same receptor activity is also implicated in the rare risk of priapism.

Can trazodone be taken every night?

Many patients do use trazodone nightly for sleep, and it is considered safer for long-term nightly use than benzodiazepines. However, tolerance to the sedating effects can develop over time in some individuals, and long-term use should be discussed with a healthcare provider. Good sleep hygiene practices and cognitive behavioral therapy for insomnia (CBT-I) are considered the gold standard first-line treatments.