What Is Nitroglycerin? - Definition, Uses & Side Effects

Instructor: Brenda Ware
Follow a man who is having a heart attack. See how the healthcare providers use nitroglycerin in a variety of forms to help him during the acute (emergent) situation and long term. Learn as the nurses monitor him for desired effects and side effects of this powerful drug.


Nitroglycerin is a yellow liquid that is used as an explosive in large doses but is used medically in miniscule doses as a vasodilator (makes the blood vessels get wider).

Uses of Nitroglycerin

Nitroglycerin (NTG) is used to treat people with angina (chest pain), myocardial infarction (heart attack) , congestive heart failure (CHF), and hypertension (high blood pressure).


Mr. Lee is a 56-year-old man who smokes heavily, is overweight, has uncontrolled diabetes, and is non-compliant taking his medication for high blood pressure (BP). He has been working in his yard when he notices he has pain on the left side of the chest. It goes away when he stops and rests but recurs when he starts working again. The pain progressively gets worse. He asks his wife to take him to the hospital.

Emergency room nurses give him a NTG tablet to melt under his tongue (sublingual). He also could received a sublingual (SL) dose as a spray. NTG is given to open up the vessels in the heart that are blocked allowing more blood to flow to the damaged heart tissue. It is given under the tongue so that it can be absorbed rapidly.

NTG Sublingual Tablets

NTG Sublingual Spray

Diagnostic tests determine Mr. Lee had a mild heart attack. He is sent to the intensive care unit (ICU) for observation and to treat the persistent angina. The nurses administer an intravenous (in the vein) infusion of NTG (known as a drip) to keep the vessels open continuously allowing the tissue to heal.

NTG Injection

The nurses gradually lower the dose of the NTG drip, but Mr. Lee continues to have occasional chest pain requiring extra doses of sublingual NTG. Additionally, his BP increases with the pain.

Further diagnostic tests determine he has multiple vessels that have become blocked over time and he had other old heart attacks he was not aware of (silent heart attacks).

When stable, he is discharged to home but needs long-term, long acting doses of NTG to control his angina and keep his blood pressure down. He is discharged with a prescription for NTG paste (or a patch) that he leaves on his chest to be absorbed intradermally (by the skin). This method delivers a longer dose that will provide all day vasodilation, resulting in a lower BP and making the heart not have to work so hard. In addition to the paste, he is prescribed sublingual NTG tablets to use when he has acute episodes of chest pain.

NTG Paste
NTG Patch

NTG can also be taken by mouth as extended release capsules.

NTG Extended Release Capsules

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