Is Allergic Reaction to Mirabegron Common?
No, allergic reactions to mirabegron are not common, but they can occur and may be serious when they do. The FDA labeling specifically warns about angioedema (allergic swelling) as a potential serious adverse effect, though the exact incidence is not quantified in clinical trials 1.
Incidence of Allergic Reactions
True allergic reactions (angioedema) are rare but represent a serious safety concern that requires immediate discontinuation of mirabegron 1.
The FDA drug label explicitly warns that mirabegron may cause angioedema with swelling of the lips, face, tongue, or throat with or without difficulty breathing, requiring patients to stop the medication immediately and seek emergency care 1.
If involvement of the tongue, hypopharynx, or larynx occurs, mirabegron must be promptly discontinued with appropriate measures to ensure a patent airway 1.
Common Adverse Effects (Not True Allergies)
The most common adverse effects are not allergic in nature and include 2, 1:
- Hypertension: 7.5-11.3% vs 7.6% placebo 2
- Nasopharyngitis: 3.5-3.9% vs 2.5% placebo 2
- Urinary tract infections: 2.9-4.2% vs 1.8% placebo 2
- Headache: 2.1-3.2% vs 3.0% placebo 2
Skin and Hypersensitivity Reactions Reported
While not common, the following allergic-type reactions have been documented 1:
- Urticaria (hives)
- Leukocytoclastic vasculitis
- Rash and pruritus (itching)
- Purpura
- Lip edema
These skin reactions occurred in less than 1% of patients in clinical trials 1.
Real-World Safety Data
A comprehensive pharmacovigilance analysis of 18,763 mirabegron-related adverse event reports from 2012-2023 identified lip swelling and swollen tongue as unexpected significant adverse events, though the overall frequency remained low 3.
The large integrated clinical trial database of over 10,500 patients confirmed that no previously unreported safety concerns were identified, and the overall safety profile remained favorable 4.
Critical Clinical Implications
Absolute contraindication: Do not use mirabegron in patients with known allergy to mirabegron or any of its ingredients 1.
Patient counseling is essential: Patients must be instructed to immediately discontinue mirabegron and seek emergency care if they develop 1:
- Swelling of face, lips, tongue, or throat
- Hives
- Difficulty breathing
Comparison to Other Drug Classes
Unlike the high rates of allergic reactions seen with certain antibiotics (e.g., 16% hypersensitivity with carboplatin, 65-75% tolerance after fluoroquinolone reactions), mirabegron's allergic reaction profile is considerably lower 5.
The tolerability of mirabegron is generally superior to antimuscarinics, with adverse effect rates similar to placebo in most categories except for the specific concerns of hypertension and urinary retention 6.