Contraindications to Labetalol
Labetalol is absolutely contraindicated in bronchial asthma, overt cardiac failure, greater-than-first-degree heart block, cardiogenic shock, severe bradycardia, and severe/prolonged hypotension. 1
Absolute Contraindications
Cardiac Conditions
- Second or third-degree heart block without a functioning permanent pacemaker 2
- Overt cardiac failure or decompensated heart failure with signs of low output state 1
- Cardiogenic shock 1
- Severe bradycardia (heart rate <50 bpm), particularly when symptomatic 2
- Systolic heart failure in the acute setting 2
Respiratory Conditions
- Bronchial asthma - this is an absolute contraindication per FDA labeling 1
- Active bronchospasm or severe reactive airway disease 2
- Beta-blockers, even those with apparent cardioselectivity like labetalol, should not be used in patients with a history of obstructive airway disease including asthma 1
Other Absolute Contraindications
Important Clinical Context and Nuances
Asthma vs. COPD Distinction
While labetalol is absolutely contraindicated in asthma, the evidence regarding COPD is more nuanced. The key distinction is bronchial hyperreactivity with reversible airflow obstruction - if spirometry demonstrates >20% reversibility with bronchodilators, labetalol should be avoided 3. However, mild-to-moderate COPD without significant reversibility (FEV1 >50% predicted) is not an absolute contraindication to cardioselective beta-blockers, though labetalol's non-selective properties make it less ideal than pure beta-1 selective agents 4, 3.
Heart Failure Considerations
Labetalol is contraindicated in heart failure during acute decompensation 2, but this represents the acute phase only. The guideline evidence consistently shows that once patients are stabilized and euvolemic, beta-blockers provide mortality benefit in heart failure 5. However, labetalol's specific role in chronic heart failure management is limited compared to evidence-based agents like metoprolol succinate, bisoprolol, or carvedilol.
Pregnancy-Specific Guidance
In pregnancy, labetalol remains a first-line agent for hypertensive emergencies despite its contraindications 2. The cumulative dose should not exceed 800 mg/24 hours to prevent fetal bradycardia 2. Monitor fetal heart rate during administration, and if fetal bradycardia develops, timely institution of oral therapy (methyldopa or long-acting nifedipine) should be considered 2.
Relative Contraindications Requiring Caution
Diabetes Mellitus
Diabetes is not a contraindication to labetalol 3, 6. While beta-blockers can mask hypoglycemic symptoms and impair glucose control, the cardiovascular benefits outweigh risks. Patients should monitor blood glucose more frequently, particularly those on insulin or long-acting oral agents 6.
Peripheral Vascular Disease
Labetalol should be avoided only in patients with vasospastic disorders, rest pain with severe peripheral vascular disease, or nonhealing lesions 3. Mild-to-moderate peripheral arterial disease is not a contraindication, though careful surveillance for worsening claudication is warranted 3, 6.
Common Pitfalls to Avoid
Do not confuse COPD with asthma - COPD without bronchial hyperreactivity is not an absolute contraindication, while asthma always is 1, 4
Do not withhold labetalol in stable heart failure - the contraindication applies only to acute decompensation 2, 5
Do not assume all respiratory disease is a contraindication - obtain spirometry with bronchodilator testing to assess reversibility before categorically excluding labetalol 3
Monitor cumulative dosing in pregnancy - exceeding 800 mg/24h significantly increases fetal bradycardia risk 2
Recognize drug-specific toxicity - labetalol is among the more toxic beta-blockers in overdose, along with propranolol and sotalol 7