Nitrogard Side Effects

Generic Name: nitroglycerin

Note: This page contains side effects data for the generic drug nitroglycerin. It is possible that some of the dosage forms included below may not apply to the brand name Nitrogard.

It is possible that some side effects of Nitrogard may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

For the Consumer

Applies to nitroglycerin: capsule extended release, spray, tablet, tablet extended release

As well as its needed effects, nitroglycerin (the active ingredient contained in Nitrogard) may cause unwanted side effects that require medical attention.

If any of the following side effects occur while taking nitroglycerin, check with your doctor immediately:

Less common
  • Bloating or swelling of the face, arms, hands, lower legs, or feet
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • difficult or labored breathing
  • feeling faint, dizzy, or lightheadedness
  • feeling of warmth or heat
  • flushing or redness of the skin, especially on the face and neck
  • headache
  • rapid weight gain
  • shortness of breath
  • sweating
  • tightness in the chest
  • tingling of the hands or feet
  • unusual weight gain or loss
  • wheezing
  • Bluish-colored lips, fingernails, or palms
  • dark urine
  • fever
  • pale skin
  • rapid heart rate
  • sore throat
  • unusual bleeding or bruising
  • unusual tiredness or weakness
Incidence not known
  • Arm, back, or jaw pain
  • blurred vision
  • chest pain or discomfort
  • chest tightness or heaviness
  • confusion
  • cough
  • cracks in the skin
  • difficulty with swallowing
  • dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
  • fainting
  • fast, irregular, pounding, or racing heartbeat or pulse
  • feeling of constant movement of self or surroundings
  • feeling of warmth
  • hives
  • increased sweating
  • itching
  • loss of heat from the body
  • nausea or vomiting
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • rash
  • red, swollen skin
  • redness of the face, neck, arms, and occasionally, upper chest
  • scaly skin
  • sensation of spinning
  • skin rash
  • weakness

If any of the following symptoms of overdose occur while taking nitroglycerin, get emergency help immediately:

Symptoms of overdose
  • 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
  • cold, clammy skin
  • disturbed color perception
  • double vision
  • flushed skin
  • halos around lights
  • headache, severe and throbbing
  • increased sweating
  • loss of appetite
  • loss of consciousness
  • night blindness
  • overbright appearance of lights
  • paralysis
  • slow or irregular heartbeat
  • tunnel vision

Some nitroglycerin side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Less common
  • Abdominal or stomach pain
  • body aches or pain
  • congestion
  • hoarseness
  • lack or loss of strength
  • runny nose
  • sneezing
  • stuffy nose
  • tender, swollen glands in the neck
  • voice changes

For Healthcare Professionals

Applies to nitroglycerin: buccal tablet extended release, intravenous solution, oral capsule extended release, rectal ointment, sublingual spray, sublingual tablet, transdermal film extended release, transdermal ointment

Nervous system

Nervous system side effects commonly include headaches and lightheadedness in 2 to 50% of patients, which may be severe, but may become less intense after 2 weeks of therapy. Some intravenous preparations of nitroglycerin (the active ingredient contained in Nitrogard) contain alcohol. Rare cases of alcohol intoxication have been reported in some patients after prolonged, high dose administration of intravenous nitroglycerin.

Headaches are the result of intracranial vasodilation and increased intracranial pressure. Rare cases of increased intracranial pressure, resulting in papilledema, diplopia, 6th cranial nerve palsy, and decreased mental status have been reported.

Rare cases of Wernicke's encephalopathy have been reported, thought to be due to the ethyl alcohol and propylene glycol vehicle used in some intravenous preparations of nitroglycerin.

A case of ageusia associated with transdermal nitroglycerin has been reported.


In a review of 17 cases of hypotensive bradycardia following nitroglycerin (the active ingredient contained in Nitrogard) administration, no reliable factors to predict this side effect were found. The mechanism is thought to be vasovagal; atropine is an effective countermeasure. There is evidence that right ventricular (RV) dysfunction, particularly in the event of RV myocardial infarction (MI), may predispose patients to develop hypotension during nitroglycerin administration. These patients are extremely sensitive to changes in preload and may have preexisting bradycardia. Therefore, caution is recommended if nitroglycerin is necessary in patients with RV or inferior wall MI.

Rare cases of A-V block, including complete heart block, thought to be vasovagally-mediated after nitroglycerin administration, have been reported.

Nitroglycerin may aggravate angina associated with hypertrophic cardiomyopathy.

Nitroglycerin may induce vasodilation in poorly ventilated areas of the lung, which may result in hypoxemia.

In some cases, coronary artery stenoses have appeared paradoxically worsened angiographically after administration of nitroglycerin. The mechanism by which nitroglycerin may induce myocardial ischemia is not known. It may cause coronary artery vasodilation and a local "steal phenomenon" or it may cause a greater degree of venous pooling than coronary artery dilation, resulting in an imbalance of myocardial perfusion.

Nitroglycerin transdermal patches should be removed prior to DC cardioversion. Cases of electrical arcing from the paddles to the aluminum patch backing have been reported.

Some intravenous preparations of nitroglycerin, such as Tridil, contain 100 mEq/L potassium (K+), which may cause hyperkalemia and an increased risk of arrhythmias. When using such preparations, monitor the serum K+ and heart rhythm closely.

Cardiovascular side effects include bradycardia, hypotension, or syncope in less than 5% of patients. Hypotension associated with intravenous nitroglycerin is reported in up to 18% of patients, but may be more likely in cases of right ventricular or inferior wall infarction. Nitroglycerin may induce reflex tachycardia in less than 1% of patients.

Rarely, myocardial ischemia or pedal edema have been associated with nitroglycerin.

Rare cases of increased arteriolar-alveolar (Aa) O2 differences have been reported. It is recommended that nitroglycerin be given with caution to patients with pneumonia and preexisting lung disease.

Tolerance to the cardiovascular effects of nitrates has been reported.


Gastrointestinal complaints of mild nausea occur in less than 1% after orally-ingested nitroglycerin (the active ingredient contained in Nitrogard)


An unusual hematologic side effect is the development of methemoglobinemia, almost exclusively reported after doses greater than 30 mcg/kg/min were given for several days. Nitroglycerin (the active ingredient contained in Nitrogard) may prolong bleeding times via a prostacyclin mechanism.

Methemoglobinemia may be asymptomatic, but should be suspected if the patient's blood appears dark to gross examination or if the patient appears cyanotic. Patients with ischemic heart disease may experience angina pectoris. The diagnosis is confirmed by measurement of arterial methemoglobin concentration, and therapy consist of withdrawal of nitroglycerin, if possible, oxygen therapy, and 1 to 2 mg/kg of 1% methylene blue intravenously over 10 minutes. If the response is inadequate, methylene blue may be repeated in 1 hour.


Dermatologic reactions have occasionally been associated with transdermal patches. Cases of mild and severe contact dermatitis manifest as erythema, pruritus, and burning have been reported, as well as rare cases of lichen planus. Hypersensitivity rashes have rarely been associated with orally administered nitroglycerin (the active ingredient contained in Nitrogard)

The cause of some cases of dermatitis may not be nitroglycerin, per se, but another material used in the patch itself.

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