Side Effects of Myrbetriq (Mirabegron)
The most common side effects of Myrbetriq (mirabegron) include hypertension, nasopharyngitis, urinary tract infection, and headache. 1
Common Side Effects
- Hypertension (7.5-11.3% with 25-50mg doses) - occurs more frequently in patients with baseline hypertension 1
- Nasopharyngitis (3.5-3.9%) 1
- Urinary tract infection (2.9-4.2%) 1
- Headache (2.1-3.2%) 1
- Constipation (1.6%) 1
- Upper respiratory tract infection (1.5-2.1%) 1
- Arthralgia (1.3-1.6%) 1
- Diarrhea (1.2-1.5%) 1
- Tachycardia (1.2-1.6%) 1
- Abdominal pain (0.6-1.4%) 1
- Fatigue (1.2-1.4%) 1
Serious Side Effects
- Angioedema - allergic reaction with swelling of the lips, face, tongue, or throat with or without difficulty breathing (requires immediate medical attention) 1
- Urinary retention - increased risk in patients with bladder outlet obstruction 1
- Severe uncontrolled hypertension (contraindicated) 2, 1
Side Effects in Long-term Use (52 weeks)
- Hypertension (9.2%) 1
- Urinary tract infection (5.9%) 1
- Headache (4.1%) 1
- Nasopharyngitis (3.9%) 1
- Back pain (2.8%) 1
- Constipation (2.8%) 1
- Dry mouth (2.8%) - notably lower than with antimuscarinic medications 1, 3
- Dizziness (2.7%) 1
- Sinusitis (2.7%) 1
Less Common Side Effects (<1%)
- Cardiac disorders: palpitations, increased blood pressure 1
- Eye disorders: glaucoma, blurred vision 1
- Gastrointestinal disorders: dyspepsia, gastritis, abdominal distension 1
- Infections: sinusitis, rhinitis 1
- Laboratory abnormalities: increased GGT, AST, ALT, LDH 1
- Renal and urinary disorders: nephrolithiasis, bladder pain 1
- Reproductive system disorders: vulvovaginal pruritus, vaginal infection 1
- Skin disorders: urticaria, leukocytoclastic vasculitis, rash, pruritus, purpura, lip edema 1
Side Effects Leading to Discontinuation
The most frequent adverse events leading to discontinuation (≥0.2%) include 1:
- Nausea
- Headache
- Hypertension
- Diarrhea
- Constipation
- Dizziness
- Tachycardia
Special Considerations
Cardiovascular Considerations
- Regular blood pressure monitoring is recommended, especially during the initial treatment period 2
- Contraindicated in patients with severe uncontrolled hypertension 2, 1
- Cerebrovascular accident was reported as a serious adverse event in 0.4% of patients in long-term studies 1
Drug Interactions
- Mirabegron is a moderate CYP2D6 inhibitor and may increase systemic exposure to CYP2D6 substrates (e.g., thioridazine, flecainide, propafenone, digoxin) 1
- Appropriate monitoring and dose adjustment may be necessary when using these medications concurrently 1
Special Populations
- In geriatric patients, the most common adverse events include hypertension, urinary tract infections, headache, and nasopharyngitis 2
- Dose reduction is needed in patients with severe renal failure or moderate hepatic failure 1
- Caution is advised when prescribing to frail elderly patients who may have a higher adverse event profile 2
Advantages Over Antimuscarinic Medications
- Significantly lower incidence of dry mouth (2.8% vs 8.6% with antimuscarinics) 1, 3
- Lower rates of constipation and urinary retention compared to many antimuscarinic agents 3
- Similar overall efficacy to antimuscarinic medications with better tolerability profile 4, 3