Bupropion’s most common side effects are insomnia and dry mouth, with trouble sleeping affecting up to 40% of people in clinical trials. Most side effects are mild and tend to ease within the first few weeks of treatment, but some, like seizure risk at high doses, are serious enough to warrant attention.
The Most Common Side Effects
In FDA clinical trials, insomnia was the standout complaint. Roughly 31% to 40% of people taking bupropion reported trouble sleeping, compared to about 18% to 21% on placebo. That gap is significant and makes sleep disruption the single most likely side effect you’ll notice. Because bupropion is a stimulating antidepressant rather than a sedating one, taking your dose earlier in the day (and avoiding evening doses if you take it twice daily) can help reduce its impact on sleep.
Dry mouth is the second most common issue, affecting about 10% to 11% of users versus 4% to 5% on placebo. After that, the list includes constipation (8%), nausea (9%), dizziness (8% to 10%), difficulty concentrating (9%), and anxiety (8%). Less frequent but still notable: reduced appetite, tremor, joint pain, muscle aches, skin rash, and an unusual taste in the mouth.
Many of these side effects overlap with symptoms people already experience from depression or anxiety itself, which can make it hard to tell what’s the medication and what’s the condition. Tracking your symptoms during the first few weeks gives you a clearer picture.
Weight Changes
Unlike many antidepressants that cause weight gain, bupropion tends to have the opposite effect. A 2024 meta-analysis of 25 randomized trials with over 12,000 participants found that bupropion led to an average weight loss of about 3.7 kilograms (roughly 8 pounds) compared to placebo. In real-world clinical settings, about 5% loss of baseline body weight at six months is typical. This is one reason bupropion is sometimes chosen specifically for people concerned about antidepressant-related weight gain, and it’s also an active ingredient in a dedicated weight-loss medication when combined with naltrexone.
Decreased appetite is part of the picture here. It’s listed as a common side effect but doesn’t usually require medical attention on its own.
Sexual Side Effects
One of bupropion’s advantages over SSRIs (the most commonly prescribed class of antidepressants) is its low rate of sexual side effects. Problems like reduced desire, difficulty with arousal, or trouble reaching orgasm are hallmarks of SSRI therapy, but bupropion works through different brain chemistry and largely avoids these issues. This difference is well established enough that bupropion has been studied as an add-on treatment to counteract SSRI-induced sexual dysfunction, though results from controlled trials on that specific use have been mixed.
Seizure Risk
Seizures are the most clinically significant risk associated with bupropion. At doses up to 450 mg per day, the seizure rate is approximately 0.4%, or about 4 in every 1,000 people. That risk jumps nearly tenfold at doses between 450 and 600 mg per day, which is why there’s a firm maximum recommended dose.
Several factors raise seizure risk further: a history of seizures or epilepsy, eating disorders (particularly bulimia or anorexia), heavy alcohol use, or abruptly stopping alcohol or sedatives. The risk also increases if individual doses are too large or taken too close together. This is why bupropion is prescribed in divided doses or extended-release formulations that release the drug gradually.
Blood Pressure and Heart Effects
Bupropion can raise blood pressure in some people. In clinical trials, hypertension showed up at rates of 1% to 2%, compared to 0% on placebo. Palpitations (a noticeable or irregular heartbeat) occurred in about 2% of users. These effects are usually modest, but if you already have high blood pressure, periodic monitoring makes sense, especially during the first few months. Irregular heartbeats and restlessness are also listed among the more common side effects.
Mental Health Effects
Bupropion carries an FDA boxed warning (the most serious category) about increased risk of suicidal thoughts and behavior in children, adolescents, and young adults. This warning applies to all antidepressants, not bupropion specifically. Clinical trials did not show this increased risk in adults over 65. The warning emphasizes close monitoring when starting or adjusting doses, particularly in younger patients.
Beyond the boxed warning, anxiety, nervousness, irritability, and agitation are recognized side effects. In trials, anxiety affected about 8% of bupropion users compared to 6% on placebo. Vivid or abnormal dreams were reported by about 5% of people. Some users also describe a “wired” or overstimulated feeling, especially in the first week or two, which often settles as the body adjusts.
Skin Reactions
Skin-related side effects are relatively uncommon but worth knowing about. Rash appeared in 3% to 4% of trial participants, itching in about 3%, and dry skin in about 2%. Hives (urticaria) occurred in roughly 1%. In rare cases, bupropion can trigger a more serious allergic reaction involving swelling of the face or throat, which requires immediate medical attention.
What to Expect in the First Few Weeks
Most side effects from bupropion are front-loaded. They tend to be strongest during the first one to two weeks as your body adjusts, then gradually diminish. Insomnia and dry mouth are the most persistent, but even these often improve with time or simple adjustments like shifting your dosing schedule earlier in the day, staying hydrated, or using sugar-free gum for dry mouth. Nausea and dizziness, when they occur, typically resolve within the first couple of weeks.
If you’re taking bupropion twice daily and struggling with insomnia, spacing your second dose as far from bedtime as possible (at least 8 hours) can make a noticeable difference. Extended-release versions, taken once in the morning, are often better tolerated for sleep.