Nitroglycerin: Uses, side effects & interactions!

Nitroglycerin also known as glyceryl trinitrate is a medication used for lowering the blood pressure.


  • Angina
  • Hypertension
  • Acute myocardial infarction
  • Acute coronary artery spasms
  • Pulmonary edema
  • Tendonitis
  • Anal fissure
  • Pain management in menstrual cramps
  • Heart failure.


Dosage forms available:

  • Sublingual tablet: 0.3 mg, 0.4 mg, 0.6 mg
  • Oral capsule (XR): 2.5 mg, 6.5 mg, 9 mg
  • Aerosol spray: 400 mcg (0.4 mg)/ spray
  • Rectal ointment: 0.4 %
  • Transdermal ointment: 2%
  • Transdermal patch: 0.1 mg/hr, 0.2 mg/hr, 0.4 mg/hr, 0.6 mg/hr
  • Intravenous IV solution: 5 mg/ml, 25 mg/200 ml, 50 mg/200 ml, 100 mg/200 mg

Dosage guidelines:

  • Angina: 2.5-6.5 mg tablet every 4 hours, depending on severity.
  • CAD: 0.3-0.4 mg sublingual powder/tablet.
  • Anal fissure, chronic (0.4% ointment): Intra-anal: 1 inch (equals 1.5 mg of nitroglycerin) every 12 hours for up to 3 weeks.

Missed dose:  Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

a) Administration of activated charcoal.
b) Breathing aid by mechanical ventilation.
c) Dialysis & maintenance of hydration.


  • Headache
  • Drowsiness/Dizziness
  • Vertigo
  • Syncope
  • Low blood pressure
  • Nausea & vomiting
  • Dry mouth
  • Abdominal pain
  • Rash
  • Weakness
  • Anaphylactic reaction.


Some adverse effects observed due to overdose of nitroglycerin are:

  • Bluish-colored lips, fingernails, or palms
  • Blurred or loss of vision
  • Bulging soft spot on the head of an infant
  • Change in consciousness
  • Change in the ability to see colors, especially blue or yellow
  • Difficulty breathing
  • Flushed skin
  • Headache, severe and throbbing
  • Increased sweating
  • Loss of appetite
  • Paralysis
  • Slow or irregular heartbeat.


Nitroglycerin is contraindicated & precaution is advised in patients with following conditions:

  • ¬†Hypertrophic cardiomyopathy (HCM)
  • Tolerance developed to drug
  • Constructive pericarditis
  • Aortic stenosis
  • Mitral stenosis
  • Dehydration
  • Diarrhea
  • Low blood electrolytes
  • Anemia
  • Trauma to the head
  • Circulatory failure
  • Liver impairment
  • Renal impairment
  • Allergy to the drug.


  • Alcohol along with nitroglycerin can enhance the vasodilatory effect of the drug.
  • When used along with or in presence of sildenafil, the vasodilatory effects are enhanced.
  • Oral nitroglycerin when given along with ergotamine, can increase the bioavailability of the latter.
  • Anticholinergic agents may decrease the absorption of nitroglycerin.
  • Topical dapsone may enhance the adverse effects like methemoglobinemia.
  • Adverse effects of local anesthetic drugs are enhanced in its presence.
  • Vasodilators (Organic Nitrates) like nitroglycerin may enhance the adverse/toxic effect of Rosiglitazone.
  • Nitroglycerin may diminish the serum concentration & anticoagulant effect of Heparin.


  • Pregnancy: Nitroglycerin is used in pregnant women after they have given birth for stabilizing of uterine contraction. IV doses can be given in hypertension in pregnant women.
  • Breast Feeding: No clear relationship in breast feeding mothers is established.
  • Children: The drug is used in children in conditions such as high blood pressure at low controlled doses.