Wellbutrin (bupropion) causes a distinct set of side effects compared to other antidepressants, largely because it works on different brain chemistry. Instead of targeting serotonin like most antidepressants, it boosts norepinephrine and dopamine, two chemicals involved in energy, focus, and motivation. This gives it a more activating profile, meaning its most common side effects lean toward feeling wired rather than sluggish.
The Most Common Side Effects
In clinical trials with 323 patients, the side effects that showed up significantly more often than placebo were dry mouth (16% vs. 7%), nausea (12.5% vs. 7.5%), and insomnia (10.5% vs. 6.5%). These three are the ones you’re most likely to notice in the first weeks of treatment.
Dry mouth and constipation come from the drug’s effect on norepinephrine, while insomnia ties back to its dopamine activity. Taking your dose earlier in the day, rather than in the evening, is a standard strategy for reducing sleep disruption. Nausea is generally transient and tends to fade as your body adjusts.
Agitation and Anxiety
This is one side effect that catches people off guard. Agitation was reported by nearly 32% of patients in clinical trials, compared to 22% on placebo. That’s a meaningful difference. Some people describe it as a jittery, restless feeling, an inner sense of being keyed up that makes it hard to sit still. A smaller number (about 3%) report noticeable anxiety beyond what they had at baseline.
These effects are more common during the first few weeks and often settle down. For a minority of patients, though, the agitation persists and becomes a reason to switch medications. If you already deal with significant anxiety alongside depression, this is worth discussing before starting treatment, since the activating quality of Wellbutrin can temporarily amplify that feeling.
Weight Changes
Unlike many antidepressants that cause weight gain, Wellbutrin tends to produce modest weight loss. A 52-week study found that the amount of weight lost correlated with starting body weight. People with a BMI under 22 lost an average of just 0.1 kg over the course of treatment, while those with a BMI of 30 or higher lost an average of 2.4 kg (about 5 pounds).
This isn’t dramatic weight loss, but the trend runs in the opposite direction of SSRIs, which commonly add pounds over time. It’s one of the reasons prescribers sometimes choose Wellbutrin for patients who’ve gained weight on other antidepressants.
Sexual Side Effects Are Uncommon
One of the clearest advantages of Wellbutrin over SSRIs is its sexual side effect profile. SSRIs like sertraline, fluoxetine, and paroxetine frequently cause reduced desire, difficulty with arousal, or trouble reaching orgasm. Wellbutrin has the lowest rate of sexual side effects among commonly prescribed antidepressants, and it’s sometimes added alongside an SSRI specifically to counteract those problems.
If sexual side effects are a dealbreaker for you on other antidepressants, this is a meaningful distinction worth raising with your prescriber.
Seizure Risk
Seizures are the most serious side effect associated with Wellbutrin, and the risk is directly tied to dose. At doses up to 300 mg per day (the sustained-release form), the seizure rate is approximately 0.1%, or 1 in 1,000 people. At 300 to 450 mg per day with the immediate-release formulation, that rises to about 0.4%. Above 450 mg per day, the risk increases almost tenfold.
This is why prescribers rarely exceed 450 mg daily and why the medication is taken in divided doses rather than all at once. People with a history of seizures, eating disorders (which lower seizure threshold), or heavy alcohol use face higher risk. Alcohol is a particular concern: drinking regularly and then stopping abruptly while on Wellbutrin can further increase seizure susceptibility.
Alcohol and Wellbutrin
Mixing Wellbutrin with alcohol creates a two-sided problem. Alcohol is a brain depressant, and it can reduce the antidepressant’s effectiveness, meaning your depression symptoms may return or worsen. At the same time, the combination increases your risk of seizures and can intensify side effects like nausea, dizziness, blurred vision, and headaches.
There’s also a less obvious risk: if you’ve been drinking regularly and stop while taking Wellbutrin, the withdrawal process itself can lower your seizure threshold further. This combination of alcohol withdrawal and bupropion can trigger seizures, tremors, confusion, and loss of coordination. If you drink regularly, it’s important to be upfront about that before starting this medication.
FDA Warning on Suicidal Thinking
Wellbutrin carries the same boxed warning as all antidepressants regarding suicidal thoughts and behavior, particularly in younger people. The risk is highest in children, adolescents, and young adults ages 18 to 24. Pooled data across antidepressant trials puts the numbers in perspective: among patients under 18, there were 14 additional cases of suicidal thinking per 1,000 patients treated, compared to placebo. For ages 18 to 24, the figure was 5 additional cases per 1,000.
In adults 25 to 64, antidepressants were actually associated with 1 fewer case per 1,000, and in adults 65 and older, 6 fewer cases per 1,000. The risk is real but concentrated in younger age groups, and close monitoring during the first weeks of treatment is standard practice.
When Side Effects Typically Fade
Most of the uncomfortable but non-dangerous side effects, particularly nausea, jitteriness, and trouble sleeping, are front-loaded in the first few weeks of treatment. Nausea is generally transient. Agitation and anxiety are more common early on and improve as your body adjusts, though a small number of people find they persist.
The general pattern is that weeks two through four are the roughest, and by six to eight weeks, many of the activating side effects have calmed down. Some effects like dry mouth and insomnia can linger longer, especially at higher doses.
Stopping Wellbutrin
Wellbutrin has a milder discontinuation profile than SSRIs, but stopping abruptly can still cause withdrawal symptoms. Reported symptoms include anxiety, sleep disturbances, irritability, headaches, muscle pain, fatigue, dizziness, and drowsiness. These can appear within a couple of days of stopping the medication.
A gradual taper, sometimes stepping down to every-other-day dosing before stopping entirely, helps reduce these effects. If you’re planning to stop, doing it under guidance rather than on your own makes the process smoother and lowers the chance of rebound symptoms.