Wellbutrin (bupropion) causes dry mouth, insomnia, nausea, and headaches more often than any other side effects. In clinical trials, roughly 1 in 4 patients reported dry mouth and nausea, and about 1 in 5 experienced insomnia. Most of these effects ease within the first few weeks, though some can persist longer.
How Wellbutrin Works Differently
Wellbutrin isn’t an SSRI. Instead of targeting serotonin, it boosts two other brain chemicals: norepinephrine and dopamine. That distinction matters because it shapes which side effects you’re likely to experience. The norepinephrine boost is what drives dry mouth, agitation, and occasional blood pressure increases. The dopamine boost contributes to insomnia, constipation, and a “wired” feeling some people notice early on.
This mechanism is also why Wellbutrin has a notably different relationship with sexual side effects. SSRIs like sertraline and fluoxetine are the most likely antidepressants to cause problems with libido, arousal, or orgasm. Wellbutrin is among the least likely. It’s sometimes even added alongside an SSRI specifically to counteract sexual side effects caused by that other medication.
The Most Common Side Effects
FDA clinical trial data from 323 patients on Wellbutrin (compared to 185 on placebo) gives a clear picture of what to expect:
- Dry mouth: 27.6% of patients, versus 18.4% on placebo
- Headache: 25.7%, versus 22.2% on placebo
- Nausea or vomiting: 22.9%, versus 18.9% on placebo
- Insomnia: 18.6%, versus 15.7% on placebo
Notice that a fair number of placebo patients reported these same symptoms, which means the drug itself is responsible for only a portion of the cases. For insomnia, for example, the difference between the drug group and the placebo group was only about 3 percentage points. Dry mouth shows the largest gap, about 9 points, making it the side effect most clearly tied to the medication itself.
Agitation and anxiety are also common, reported in anywhere from 2% to 32% of patients depending on the study and dose. Tremor shows a similar range, affecting 1% to 21%. These wide ranges reflect different doses and formulations. Higher doses and the immediate-release version tend to produce more of these stimulatory effects.
When Side Effects Typically Fade
Most people notice the strongest side effects in the first one to two weeks. Physical symptoms like nausea, headache, and the jittery “too much coffee” feeling usually settle down as your body adjusts. Sleep disruption can take a bit longer to resolve, especially if you’re taking your dose later in the day.
Positive changes can show up before mood fully improves. Better sleep, more energy, and a normalized appetite are often the first signs the medication is working. The full psychological benefit, the actual lift in depressed mood, can take up to eight weeks. That gap between “side effects hit” and “benefits arrive” is the hardest stretch for most people starting the medication.
Seizure Risk
The most well-known serious risk with Wellbutrin is seizures. At doses up to 450 mg per day, the seizure rate is about 0.4%, or 4 out of every 1,000 patients. That risk jumps nearly tenfold at doses between 450 and 600 mg per day, which is why 450 mg is the maximum prescribed dose.
Certain conditions raise this risk further. Wellbutrin is contraindicated (meaning it should not be prescribed at all) for people with a seizure disorder, a current or past diagnosis of anorexia or bulimia, or anyone going through abrupt withdrawal from alcohol, benzodiazepines, or barbiturates. Eating disorders in particular are flagged because they were linked to a higher incidence of seizures in patients taking the drug.
Alcohol and Wellbutrin
Mixing alcohol with Wellbutrin is considered unsafe at any amount. Even one or two drinks can increase seizure risk. This isn’t just a general “be careful” warning. Alcohol lowers the seizure threshold on its own, and combining it with a medication that already carries seizure risk compounds the danger.
There’s an additional concern that catches some people off guard: if you’ve been drinking regularly and then stop while on Wellbutrin, the withdrawal itself raises seizure risk even more. This creates a situation where both drinking and suddenly quitting drinking are problematic. If you drink regularly and are starting Wellbutrin, that’s something to discuss honestly with your prescriber so you can taper safely.
The FDA Warning on Suicidal Thoughts
Wellbutrin carries a boxed warning, the most serious type the FDA issues, about suicidal thoughts and behaviors. This warning applies to all antidepressants, not just Wellbutrin. Pooled data from clinical trials showed that young adults ages 18 to 24 had about 5 additional cases of suicidal thinking per 1,000 patients treated, compared to placebo. Adults over 24 did not show this increased risk, and adults 65 and older actually showed a reduced risk compared to placebo.
This doesn’t mean the medication causes suicidal behavior in most people. It means the early weeks of treatment are a period that requires close attention, particularly for younger adults. New or worsening thoughts of self-harm, sudden mood shifts, or unusual agitation in the first weeks are signals to contact your prescriber promptly.
Who Should Avoid Wellbutrin
Beyond the seizure-related contraindications, Wellbutrin is not appropriate for people currently taking or recently stopping an MAO inhibitor (another class of antidepressant), or for those with a history of seizures. The eating disorder restriction is specific: both bulimia and anorexia nervosa, whether current or in the past, are listed as contraindications because the nutritional and metabolic disruptions tied to those conditions appear to make bupropion-related seizures more likely.
People with severe head injuries, brain tumors, or a history of severe stroke are also flagged as higher risk due to their already-lowered seizure threshold.