Side Effects of Carvedilol
Carvedilol is generally well tolerated, with most adverse events being mild to moderate and related to its dual alpha- and beta-blocking properties, including dizziness (5.5% higher than placebo), hypotension (8.6%), fatigue, and bradycardia, though importantly, beta-blockers including carvedilol show no meaningful increase in overall adverse event rates compared to placebo in heart failure trials. 1
Cardiovascular Side Effects
Hypotension and Dizziness:
- Hypotension occurs in 8.6% of patients and is typically seen within 24-48 hours of the first dose or dose increases, usually resolving with repeated dosing without dose changes 1, 2, 3
- Dizziness occurs at a 5.5% higher rate compared to placebo, increasing from 2% to 5% as doses escalate from 6.25 mg to 50 mg daily 1
- These vasodilatory effects result primarily from alpha-1 receptor blockade and may present with lightheadedness or blurred vision 1, 3
- Management: Administer carvedilol and ACE inhibitors at different times during the day, reduce diuretic doses in volume-depleted patients, or temporarily reduce ACE inhibitor dose 1, 2
Bradycardia and Heart Block:
- Bradycardia occurs in 9.3% of patients 1
- Heart rate slowing is generally asymptomatic and requires no treatment unless accompanied by dizziness, lightheadedness, or second/third-degree heart block 1
- If heart rate drops below 55 bpm, consider dose reduction; if below 50 bpm or symptomatic, hold or reduce the dose temporarily 4
Neurological Side Effects
- Fatigue occurs in 7.1% of patients (not significantly different from placebo) 1
- Headache occurs in 8.2% of patients 1
- General lassitude may resolve spontaneously within several weeks but can be severe enough to limit dose increases or require withdrawal 1
- Insomnia occurs in 2% of patients 3
Gastrointestinal Side Effects
- Diarrhea occurs in 2% of patients and 11.9% in some trials 1, 3
- Nausea occurs in 8.6% of patients 1
- Vomiting occurs in 6.6% of patients 1
Respiratory Side Effects
- Dyspnea occurs in 4.8% of patients (not significantly different from placebo) 1
- Bronchospasm can occur, particularly in patients with asthma or COPD 3
- Upper respiratory tract infections occur in 19.1% of patients 1
Metabolic Side Effects
- Hyperglycemia occurs in 12.6% of patients 1
- Carvedilol may mask symptoms of hypoglycemia, especially tachycardia, in diabetic patients 3
- Carvedilol may mask symptoms of hyperthyroidism 3
- Weight gain occurs in 10.2% of patients 1
Other Notable Side Effects
- Peripheral edema occurs in 1% of patients 3
- Chest pain occurs in 3.9% of patients 1
- Rare but serious allergic reactions including hives or angioedema with swelling of face, lips, tongue, and/or throat that may cause difficulty breathing or swallowing 3
- Fewer tears or dry eyes that may be bothersome for contact lens wearers 3
- Thrombocytopenia occurs in 1% of patients 3
- Increased hepatic enzymes (0.2% in hypertension patients, 0.4% in heart failure patients discontinued therapy due to this) 3
Discontinuation Rates
- Overall discontinuation due to adverse events: 13.7% with carvedilol versus 12.4% with placebo in heart failure trials 1
- In hypertension trials: 4.9% discontinued carvedilol versus 5.2% discontinued placebo 3
- Hypotension was the only cause of discontinuation >1% and occurring more often with carvedilol (1.5%) versus placebo (0.2%) in post-MI patients 3
Critical Safety Considerations
Abrupt withdrawal of carvedilol can lead to clinical deterioration and should be avoided; if discontinuation is necessary, taper the dose gradually over time 1, 3
Contraindications include: severe heart failure requiring ICU care or inotropic support, asthma or severe breathing problems, severe bradycardia or heart block, and severe liver problems 3
Special monitoring required for: patients with diabetes (blood sugar changes), thyroid disorders (masked hyperthyroidism symptoms), peripheral vascular disease (may worsen symptoms), and those scheduled for cataract surgery 3