Constipation is More Common with SNRIs than Wellbutrin
SNRIs are more likely to cause constipation than Wellbutrin (bupropion). This is supported by clinical evidence and medication profiles of both drug classes.
Comparison of Constipation Risk
SNRIs
- SNRIs commonly cause constipation as a side effect due to their noradrenergic effects 1
- Constipation is specifically listed as a common adverse effect in the FDA label for venlafaxine (an SNRI) 2
- SNRIs have anticholinergic effects that contribute to constipation, with dry mouth, constipation, and sweating being more frequent with SNRIs than with SSRIs 1
- In the treatment of gastroparesis, duloxetine (an SNRI) is noted to potentially cause or worsen constipation 3
- SNRIs like duloxetine are specifically mentioned in clinical guidelines as medications that can cause constipation as a side effect 3
Wellbutrin (Bupropion)
- Constipation is not listed among the most common side effects of bupropion in its FDA label 4
- The most common side effects of bupropion include trouble sleeping, anxiety, stuffy nose, nausea, dry mouth, dizziness, and joint aches, with constipation being less prominently mentioned 4
- While there are case reports of severe constipation with bupropion 5, this appears to be less common than with SNRIs
Clinical Implications
- When selecting between these medications for patients at risk of constipation, bupropion may be preferable 3
- For patients with IBS-C (irritable bowel syndrome with constipation), secondary amine TCAs may be better tolerated than SNRIs due to their lower anticholinergic effects 3
- The constipating effects of SNRIs should be particularly considered in patients already at risk for gastrointestinal hypomotility 3
Management of Medication-Induced Constipation
- Taking SNRIs with food may help reduce gastrointestinal side effects including constipation 6
- For patients who develop constipation on SNRIs, increasing fluid intake, physical activity, and adding fiber to the diet may help manage symptoms 3
- In severe cases of medication-induced constipation, laxatives may be necessary, starting with stimulant laxatives with or without stool softeners 3
Conclusion
When comparing the constipation risk between SNRIs and Wellbutrin, the evidence indicates that constipation occurs more frequently with SNRIs. This difference should be considered when selecting antidepressants, particularly for patients who may be predisposed to constipation or have existing gastrointestinal conditions.