Trazodone’s most common side effects are drowsiness, dizziness, and dry mouth. In clinical trials, drowsiness affected roughly 24% of hospitalized patients and 41% of outpatients, making it the single most frequent complaint. These numbers explain why trazodone is prescribed far more often as a sleep aid than as an antidepressant, even though it was originally developed for depression.
The Most Common Side Effects
In placebo-controlled trials submitted to the FDA, three side effects stood out clearly above placebo rates:
- Drowsiness: 24–41% of patients, compared to 6–20% on placebo
- Dizziness or light-headedness: 20–28%, compared to 5–15% on placebo
- Dry mouth: 15–34%, compared to 8–20% on placebo
Constipation and blurred vision also appeared at roughly twice the rate of placebo, though less frequently than the top three. Many people also report nausea, headache, or fatigue, particularly during the first week or two of treatment before the body adjusts.
Next-Day Grogginess and Cognitive Effects
Because most people take trazodone at bedtime, the “hangover” effect the next morning is one of the most practically important side effects. A randomized, placebo-controlled study testing 50 mg nightly in people with insomnia found small but measurable impairments the following morning in short-term memory, verbal learning, balance, and arm muscle endurance. These effects persisted after a full week of nightly use, meaning they didn’t fully fade with continued dosing.
If you feel groggy or unsteady the morning after taking trazodone, that’s a recognized effect of the drug rather than just poor sleep. It can affect driving ability and reaction time, so it’s worth paying attention to how you feel before getting behind the wheel, especially during the first few days.
How Dose Changes the Picture
Trazodone behaves differently at different doses, and this matters for side effects. At lower doses (25 to 100 mg), the drug primarily blocks histamine and certain serotonin receptors, which is why it makes you sleepy. It doesn’t do much for depression at these doses.
At higher doses (150 to 600 mg), it starts blocking serotonin reuptake, which is where the antidepressant effect comes from. But those higher doses also intensify sedation and increase the risk of orthostatic hypotension, a sudden drop in blood pressure when you stand up that can cause dizziness or fainting. This dose-dependent escalation of side effects is one reason trazodone is used far more often at low doses for sleep than at the higher doses needed for depression.
Heart Rhythm Effects
Trazodone can affect the electrical timing of your heartbeat by prolonging what’s called the QT interval. Lab studies show it blocks a specific potassium channel in heart cells at clinically relevant concentrations, which is the same mechanism behind several other drugs that have been flagged for cardiac risk.
At prescribed doses, this effect is usually minor. But case reports have documented dangerous heart rhythm disturbances, including a potentially fatal pattern called torsades de pointes, even in patients taking normal doses. The risk increases substantially in overdose. If you have a pre-existing heart condition, take other medications that affect heart rhythm, or have low potassium or magnesium levels, this is something your prescriber should be factoring in.
Priapism
Trazodone carries a rare but serious risk of priapism, a persistent, painful erection unrelated to sexual arousal that lasts longer than four hours. The overall incidence is about 1.5 cases per 100,000 person-years, rising to 2.9 per 100,000 in men over 40.
Those numbers sound tiny, but the consequences are severe enough to warrant awareness. Priapism is a medical emergency. If treatment is delayed beyond 48 to 72 hours, the erection and pain may eventually resolve on their own, but permanent erectile dysfunction becomes likely. Any erection lasting more than four hours while taking trazodone requires immediate emergency care.
Serotonin Syndrome Risk
When trazodone is combined with other drugs that raise serotonin levels, it can trigger serotonin syndrome, a potentially dangerous condition marked by agitation, rapid heart rate, high blood pressure, muscle twitching, and in severe cases, high fever and seizures. Specific combinations to be cautious with include buspirone, fentanyl, lithium, tryptophan, St. John’s wort, certain migraine medications (triptans like sumatriptan), and tramadol. Other antidepressants, particularly SSRIs and SNRIs, also increase the risk if taken alongside trazodone.
This is especially relevant because trazodone for sleep is often prescribed alongside another antidepressant for depression. The combination isn’t necessarily unsafe, but it does raise the floor of serotonin-related risk, and you should know what symptoms to watch for.
Weight Changes
Trazodone is largely weight-neutral compared to many other antidepressants. In clinical trials, about 5% of people gained weight and 6% lost weight, making it close to a wash. This sets it apart from several other antidepressant classes that are strongly associated with weight gain. If weight is a concern, trazodone is generally considered one of the lower-risk options.
Stopping Trazodone
Stopping trazodone abruptly can cause withdrawal symptoms, particularly if you’ve been taking it for an extended period or at higher doses. Common discontinuation symptoms include anxiety, irritability, trouble sleeping, nausea, and general discomfort. These typically improve within a few weeks, though they can last longer for people coming off high doses after prolonged use.
A gradual taper is the standard approach. A typical schedule starts with a 10% to 25% dose reduction in the first week. For someone taking 150 mg, that might mean stepping down to 125 mg or 100 mg, then continuing to reduce in small increments over several weeks. The exact pace depends on your dose, how long you’ve been taking it, and how you respond to each reduction. Even at the low doses used for sleep, abrupt discontinuation can be uncomfortable enough that tapering is worth the effort.