Common Side Effects of Nitroglycerin and Their Management
Hypotension is the most serious potential complication of nitroglycerin therapy, which may result in reflex tachycardia and worsening myocardial ischemia, requiring careful titration and monitoring of blood pressure, especially when initiating therapy or adjusting doses. 1, 2
Cardiovascular Side Effects
- Hypotension, particularly orthostatic/postural hypotension, is a common side effect that can lead to dizziness, lightheadedness, and fainting, especially when standing up quickly 1, 3
- Reflex tachycardia may occur as a compensatory response to hypotension 1, 2
- Paradoxical bradycardia may accompany nitroglycerin-induced hypotension in some patients 3
- Flushing is a common cardiovascular effect due to vasodilation 1
Neurological Side Effects
- Headache is the most frequent side effect of nitroglycerin therapy and often causes compliance issues 2, 4
- The headache may be dose-dependent and is more common in patients with migraine history 4
- Two types of headaches can occur:
- Dizziness and lightheadedness, especially upon standing 3
Other Common Side Effects
- Aggravation of hypoxemia by increasing ventilation-perfusion mismatch 2
- Burning or tingling sensation in the mouth when administered sublingually 3
- Nausea and vomiting 3
- Sweating and paleness 3
- Dry mouth, which may affect dissolution of sublingual tablets 3
Serious Side Effects and Contraindications
- Severe hypotension requiring immediate intervention 2
- Nitrate tolerance with continuous use, leading to decreased efficacy 1, 5
- Contraindicated with phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil) due to risk of profound hypotension 3
- Should be used with extreme caution or avoided in patients with right ventricular infarction 2, 1
- Contraindicated in patients with severe anemia, increased intracranial pressure, or recent heart attack 3
Management of Side Effects
Managing Hypotension
- Discontinue the drug if severe hypotension occurs 2, 1
- Elevate legs to improve venous return 2, 1
- Administer rapid fluid infusion to restore blood pressure 2, 1
- Consider atropine for associated bradycardia 2, 1
- Patients should sit down when taking nitroglycerin and use caution when standing up 3
Managing Headaches
- Use the smallest effective dose to minimize headache intensity 1
- For patients requiring regular nitrate therapy, provide a nitrate-free interval (10-12 hours) to prevent tolerance and reduce headache frequency 1, 6
- Consider prophylactic migraine therapy if headaches become problematic with frequent nitroglycerin use 6
- Alternative anti-anginal medications can be considered in patients who cannot tolerate nitroglycerin-induced headaches 6
Preventing Nitrate Tolerance
- Provide a daily "nitrate-free interval" of 10-12 hours to prevent tolerance 1, 5
- Avoid continuous 24-hour administration of nitroglycerin 7
- For transdermal patches, remove at bedtime and apply a new patch in the morning 7
Monitoring Recommendations
- Regular monitoring of blood pressure, especially when initiating therapy or adjusting doses 1
- Monitor heart rate for significant changes, particularly tachycardia or bradycardia 1
- Observe for signs of tolerance, such as decreasing effectiveness in controlling angina 1, 5
- Adverse events are rare, especially in patients with systolic blood pressure >110 mmHg and heart rate <100 bpm 8
Special Populations and Precautions
- Careful titration in patients with inferior wall myocardial infarction due to frequent association with right ventricular infarction 2, 1
- Use with extreme caution in patients with right ventricular infarction as they are especially dependent on adequate right ventricular preload 2, 1
- Nitroglycerin should be avoided in the presence of marked bradycardia or tachycardia, especially if relative hypotension is present 2