When something restricts blood flow to the heart muscle, a person can experience intense chest pain that doctors call angina. People often use the drug nitroglycerin to relieve chest pain that angina causes.
Most often, the reason for the decrease in blood flow is plaque formation and narrowing of the arteries supplying blood to the heart.
Nitroglycerin helps to open up the blood vessels and allow blood to flow. People also use nitroglycerin to treat chronic anal fissures.
In this article, we provide an overview of nitroglycerin, including its uses, how it works, and the possible side effects, interactions, and warnings.
Nitroglycerin is a medication that treats angina and chronic anal fissures. It works by promoting blood flow.
The body breaks nitroglycerin down into nitric oxide. Nitric oxide causes the smooth muscle within the blood vessels to relax. This allows the arteries and veins to open up, allowing more blood to flow through. Healthcare professionals call this action vasodilation.
During an angina attack, a person will experience intense chest pain. Nitroglycerin will start working within 1 to 3 minutes, but its maximal effect occurs after 5 minutes.
When people use nitroglycerin for anal fissures, the ointment will relax the anal sphincter, which is the muscle tissue around the anus, and lower the pressure in the anus. This promotes blood flow to the area and helps heal the fissure.
Doctors usually use nitroglycerin to treat the pain that angina causes.
Narrowing of the arteries that supply the heart with blood is what causes unstable angina. Doctors call this condition coronary artery disease (CAD).
Nitroglycerin allows the blood vessels to open up, which lets oxygen and nutrient-rich blood feed the heart muscle. This action offers immediate relief from chest pain.
People can also use nitroglycerin to treat anal fissures. Anal fissures are tears in the skin of the anus. People can get anal fissures from passing hard stools.
Similarly to its effects for angina, nitroglycerin as a rectal ointment helps the healing process by stimulating blood flow to the affected area.
The following table lists the different formulations of nitroglycerin.
|Form of nitroglycerin||How to use|
| aerosol solution|
|dissolve under the tongue|
|apply to the skin|
|rectal ointment||rectal use only|
When someone is having intense chest pain, it is vitalto resolve this symptom as quickly as possible. People can also take fast-acting nitroglycerin formulations 5 to 10 minutes before doing an activity that may cause an angina attack.
The aerosol spray, pumpspray, packet, and tablet are all fast-acting forms of nitroglycerin.
Aerosol spray and pumpspray
People can use these devices by giving one or two sprays on or under the tongue once a person feels angina pains. They should not inhale the spray.
A sublingual packet of nitroglycerin contains 400 micrograms (mcg) of nitroglycerin powder. A person places the contents of the packet under their tongue when angina pains begin.
At the first signs of angina pains, a person should place the tablet under their tongue or between the gums and the cheek. The tablet will dissolve and absorb through the tissues of the mouth.
People who use the aerosol spray, pumpspray, packet, or tablet should not swallow the drug. Nitroglycerin will absorb through the mouth tissues. This provides faster relief than swallowing the medicine.
People should also avoid rinsing or spitting for 5 minutes after administering the dose.
A person can take each of these forms of fast-acting nitroglycerin at 5-minute intervals. If they do not feel relief from the intense chest pain, they can take two more doses 5 minutes apart.
If someone has taken three doses of either fast-acting formulations and does not experience any pain relief, they should seek medical attention immediately.
There are also two other formulations of nitroglycerin that can prevent angina attacks. These are not fast-acting, and people should not use them to stop an attack when it is happening.
Nitroglycerin patches come in doses ranging from 0.1 milligrams per hour (mg/hr) to 0.8 mg/hr.
A person places the patch on their skin anywhere except the areas below the knee and elbow.
Most people place the patch on their chest. The area should be clean, dry, and hairless to allow the nitroglycerin to absorb across the skin.
A person should leave the patch on the skin for 12 to 14 hours and remove it for 10 to 12 hours. People will usually have the patch on during the day and remove it during sleep.
People can apply nitroglycerin ointment to their skin using a dose-measuring applicator that comes with the tube. A person will measure the desired dose onto the measuring applicator and then place the applicator ointment side down on the skin.
They then spread the ointment across the skin. The person should not rub the medicine in but allow the ointment to absorb across the skin.
Finally, they tape the applicator to the skin.
People take two doses of ointment each day. Doctors will tell people to use the ointment first thing in the morning and then reapply it 6 hours later.
The rectal ointment for anal fissures contains 0.4% nitroglycerin. A person will insert the ointment into their anus every 12 hours for up to 3 weeks.
To apply the rectal ointment, a person will cover their finger with plastic wrap and squeeze out 1 inch of ointment along the finger.
They then insert the finger into the anal canal up to the first finger joint. The person will then smear the ointment around the area.
If this is too painful, the person may apply the ointment to the outside of the anus instead.
People may experience many side effects when using nitroglycerin, including:
When people take nitroglycerin for relieving angina, they should be in a relaxed, seated position.
An individual’s blood pressure can drop significantly after using nitroglycerin. If they stand up too quickly after administering the dose, their blood pressure may drop even lower and put them at risk of fainting.
The most common side effect of long-acting nitroglycerin is headaches, but this side effect decreases with use.
Although the rectal ointment is only put in the anus, a person may still experience headache and dizziness.
Some people may be allergic to nitroglycerin, and doctors do not recommend that people use it if they have a history of allergic reactions to nitroglycerin.
Nitroglycerin may interact with certain other medications.
PDE-5 inhibitors are drugs that doctors give to treat erectile dysfunction in males. Viagra, Cialis, and Levitra are PDE-5 inhibitors. As with nitroglycerin, these drugs also cause increased blood flow and can lower blood pressure.
Doctors do not recommend that people use nitroglycerin with PDE-5 inhibitors, as they can cause fainting if someone is taking them together.
Males should avoid using nitroglycerin if they have taken Viagra or Levitra within the last 24 hours or Cialis within the previous 48 hours.
Any person using long-acting nitroglycerin cannot take PDE-5 inhibitors.
An overdose of nitroglycerin may occur when people use PDE-5 inhibitors with nitroglycerin or if they use too much nitroglycerin during an attack.
Severe side effects that healthcare professionals associate with a nitroglycerin overdose include:
- a sudden drop in blood pressure
- increased heart rate
- increased blood flow and pressure in the brain
- throbbing headaches
- disturbances in vision
Currently, no drug can reverse a nitroglycerin overdose. Doctors can provide care to people experiencing an overdose by giving intravenous fluids and elevating their legs.
Using nitroglycerin in the appropriate way can delay the serious complications of angina that can include heart attack, stroke, and even death.
People may experience side effects with nitroglycerin and should remain seated while the drug is having its effect.
Nitroglycerin can interact with medications for erectile dysfunction. Males with angina should report the use of Viagra, Cialis, and Levitra to their doctor because the use of both drugs together may be dangerous.
People can also treat anal fissures with nitroglycerin rectal ointment. Side effects and interactions can also occur with topical use of nitroglycerin.