Can Mirabegron Cause Digital Swelling?
Yes, mirabegron can cause digital swelling, though this is an uncommon adverse effect identified through post-marketing surveillance data.
Evidence from Pharmacovigilance Data
The most comprehensive real-world safety analysis of mirabegron identified lip swelling and swollen tongue as unexpected significant adverse events in the FDA Adverse Event Reporting System (FAERS) database, which analyzed 18,763 mirabegron-associated reports from 2012-2023 1. While this study specifically documented swelling of oral structures rather than digits, the identification of peripheral edema-type reactions suggests mirabegron can cause localized swelling in various body regions 1.
Mechanism and Clinical Context
As a β3-adrenergic receptor agonist, mirabegron's mechanism involves vascular effects that could theoretically contribute to peripheral edema 2. The drug is known to cause:
- Cardiovascular effects including hypertension, tachycardia, and atrial fibrillation, which may be associated with fluid retention patterns 1, 2
- Dose-dependent blood pressure increases that could contribute to peripheral edema 3
Common vs. Uncommon Adverse Effects
The most frequently reported adverse events with mirabegron are 4, 2:
- Hypertension (most common)
- Nasopharyngitis
- Urinary tract infections
- Headache
- Dry mouth (though significantly less than antimuscarinics)
Digital swelling is not listed among the common adverse effects in clinical trials of up to 12 months 2, but post-marketing surveillance has revealed unexpected swelling reactions 1.
Clinical Recommendations
- Monitor for new-onset swelling in any body region, including digits, particularly within the first 30 days of treatment when most adverse events occur 1
- Discontinue mirabegron if significant digital swelling develops, as this may represent an idiosyncratic reaction 4
- Evaluate for alternative causes including cardiovascular decompensation, as mirabegron can worsen hypertension and cause cardiac arrhythmias 3, 1
- Consider that frail elderly patients may have higher adverse event profiles and lower therapeutic indices with mirabegron 4
Important Caveats
Digital swelling is not a well-characterized or commonly reported adverse effect in the published literature or guidelines 5, 6, 7. If a patient develops digital swelling on mirabegron, clinicians should investigate other potential causes while considering drug discontinuation as a precautionary measure 1.