Yes, constipation is a recognized side effect of Wellbutrin (bupropion). In clinical trials, about 9 to 10% of people taking the medication reported constipation, compared to just 2 to 7% of those taking a placebo. While it’s not the most common reason people stop taking the drug, it can be uncomfortable enough to affect daily life, and in rare cases it becomes severe.
How Common Constipation Is on Wellbutrin
The FDA-approved prescribing information breaks the numbers down by condition. In trials for major depressive disorder, 10% of people taking 300 mg per day reported constipation, versus 7% on placebo. Interestingly, the group taking a higher dose of 400 mg per day reported constipation at only 5%, which suggests the relationship between dose and constipation isn’t straightforward.
In separate trials for seasonal affective disorder, the gap was wider: 9% on bupropion versus 2% on placebo. The overall range reported across studies is broad, from about 8% to as high as 26% depending on the trial and formulation. That wide range likely reflects differences in how constipation was defined and measured across studies, but the consistent takeaway is that your risk is real but moderate.
Why Wellbutrin Affects Your Gut
Wellbutrin works differently from most antidepressants. Rather than targeting serotonin (the chemical most SSRIs act on), it primarily increases levels of dopamine and norepinephrine in the brain. Norepinephrine also plays a role in gut motility, the rhythmic muscle contractions that push food through your digestive tract. Higher norepinephrine activity can slow those contractions, which means stool moves through your intestines more slowly, losing more water along the way and becoming harder to pass.
This mechanism is distinct from how SSRIs affect the gut. SSRIs like sertraline and escitalopram tend to cause the opposite problem: diarrhea. That’s because serotonin speeds up gut motility. So if you’re switching to Wellbutrin from an SSRI, the shift in digestive side effects can feel especially noticeable.
When It Starts and How Long It Lasts
Most people who develop constipation on Wellbutrin notice it within the first few weeks of starting the medication or after a dose increase. For the majority of users, this side effect is temporary. Your body gradually adjusts to the medication’s effects on your nervous system, and bowel habits tend to normalize over the first month or two.
That said, some people experience persistent constipation that doesn’t resolve on its own. There are also rare case reports of severe constipation requiring medical attention, particularly with the extended-release formulation. If your symptoms are worsening rather than improving after several weeks, that’s worth bringing up at your next appointment rather than assuming it will pass.
Managing Constipation While on Wellbutrin
Simple dietary changes are the first line of defense. Adding fiber-rich foods like beans, leafy greens, whole grains, and fruit can make a noticeable difference. Staying well hydrated matters too, because fiber works by absorbing water to soften stool. If you increase fiber without drinking enough fluids, you can actually make things worse.
If food changes alone aren’t enough, a fiber supplement containing psyllium seed or methylcellulose is a gentle next step. These bulk-forming supplements are generally well tolerated for ongoing use. For more stubborn constipation, an over-the-counter osmotic laxative like polyethylene glycol (sold as MiraLAX and similar brands) draws water into the intestines and softens stool without stimulating cramping.
Physical activity also helps. Even a daily 20 to 30 minute walk can stimulate the gut muscles that move stool along. The combination of more fiber, more water, and more movement resolves constipation for most people on Wellbutrin without needing to adjust the medication itself.
How Wellbutrin Compares to Other Antidepressants
Constipation is not unique to Wellbutrin. Among antidepressants, the medications most strongly linked to constipation are certain dual-acting drugs that target both serotonin and norepinephrine. Levomilnacipran and desvenlafaxine carry the highest constipation risk, roughly three times the odds compared to placebo. Duloxetine also ranks high.
Wellbutrin’s constipation risk falls in a moderate range. If constipation is a major concern for you, it’s worth knowing that SSRIs like sertraline and escitalopram are more likely to cause diarrhea than constipation, making them a different experience entirely from a digestive standpoint. On the other hand, Wellbutrin has advantages that SSRIs don’t: it’s far less likely to cause weight gain or sexual side effects, which are two of the most common reasons people switch antidepressants. For many people, manageable constipation is a worthwhile tradeoff.