Nitroglycerin for angina: What to know

Angina pectoris, or simply angina, is chest pain that occurs when the heart muscle doesn’t receive enough oxygen-rich blood. 

To relieve the symptoms, healthcare professionals may prescribe a medication called nitroglycerin. This works in multiple ways to ensure blood flow and oxygen are effectively reaching the heart.

How does nitroglycerin work for angina?

The Food and Drug Administration (FDA) approves nitroglycerin (Nitrostat) to relieve angina symptoms. 

An older 2015 review explains how it works:

• Vasodilation: Nitroglycerin relaxes the blood vessels and lowers blood pressure. This reduces the workload and oxygen needs of the heart.
• Better blood flow: Nitroglycerin increases blood flow by dilating the blood vessels. This delivers more oxygen to the heart.
• Platelet inhibition: Nitroglycerin prevents platelets in your blood from sticking together and forming clots that can worsen angina and cause heart attacks.
• Endothelial function: Nitroglycerin substitutes nitric oxide, a natural substance that protects blood vessel linings (known as the endothelium) and helps them dilate. People with coronary artery disease usually have impaired nitric oxide production.

You can take nitroglycerin before situations that may trigger angina, such as before exercise. You can also take it when you start to experience symptoms.

Nitroglycerin (Nitrostat) is fast-acting, with a half-life of only 2–3 minutes. A half-life is how long your body takes to remove half of the medication. Generally, the body completely removes medications within five half-lives, and for nitroglycerin, this is no more than 15 minutes. 

Nitroglycerin types

Nitroglycerin (Nitrostat) is available in various forms, offering different administration options. 

Nitroglycerin tablets

Nitroglycerin tablets act quickly, providing relief from angina episodes. You can also take them as a preventive measure if you expect angina — like before exercise.

The tablets are sublingual, meaning you place them under the tongue, where they quickly dissolve.

There are typically 4 doses available:

• 0.3 milligrams (mg)
• 0.4 mg
• 0.6 mg
• 0.8 mg

You take 1 dose every 5 minutes until you feel relief from your symptoms. However, you cannot take more than 3 doses. If 3 doses do not improve your angina, you should seek emergency medical attention. 

Nitroglycerin spray

Like tablets, NitroMist offers quick relief during or before angina. 

You administer the spray under the tongue for absorption into the bloodstream. It’s important not to inhale or swallow it.

You can get a spray bottle with 100 doses of:

• 0.3 mg
• 0.4 mg
• 0.6 mg

Like the tablets, you take one or two initial doses for symptom relief, but you should not take more than three doses within 15 minutes. If you still feel angina symptoms after this time, seek immediate medical care. 

Intravenous (IV) nitroglycerin

According to a 2022 article, an emergency department can administer nitroglycerin through IV infusions. 

They may do this if you visit the emergency room with angina and your pain does not improve with dissolvable nitroglycerin tablets or sprays. 

In these cases, the medical professionals at the hospital will determine the correct dosage for your needs.

Nitroglycerin ointment

You can also get a 2% nitroglycerin ointment, Nitro-bid, to apply to the skin on your chest either before or during an angina episode. You can get different options, including:

• 30 gram (g) tube
• 60 g tube
• 48, 1 g packets

This option is most often preventive and can be useful if you find it difficult to take oral medications. 

It can take 15–30 minutes for the ointment to take effect, with the full benefits being around 60 minutes.

This medication can last up to 7 hours.

Nitroglycerin patches

You can also get Nitro-Dur transdermal skin patches that release different nitroglycerin each hour. The strengths are:

• 0.1 milligrams per hour (mg/hr)
• 0.2 mg/hr
• 0.3 mg/hr
• 0.4 mg/hr
• 0.6 mg/hr
• 0.8 mg/hr

This approach may best suit angina prevention as it offers a more sustained release of the medication. Like the ointment, it may take longer than the oral tablets or sprays to start taking effect. 

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Nitroglycerin side effects and contraindications

Nitroglycerin can cause side effects. Many of these are linked to its blood pressure-lowering effects and may include:

• severe, throbbing headaches
• fainting
• dizziness
• weakness
• irregular heartbeat
• nausea and vomiting
• excessive sweating
• flushing
• skin rash

You should not take nitroglycerin if you: 

• have already taken the maximum amount prescribed, generally 3 doses within 15 minutes
• take medication for erectile dysfunction
• have a known allergy to nitroglycerin
• have severe anemia
• have increased pressure around the brain

What is angina?

Angina is often a symptom of coronary artery disease, where the blood vessels supplying the heart become narrowed. It’s also called ischemic cardiac disease.

Other health conditions can also cause angina, such as:

• nonischemic cardiac disease, like infections affecting the heart
• gastroesophageal reflux disease
• lung disease
• musculoskeletal conditions
• mental health conditions, such as anxiety or panic attacks

Angina types

There are two main types of angina: stable and unstable.

Stable angina is when you experience symptoms from physical exertion, emotional stress, or exposure to cold temperatures. Increases in heart rate and blood pressure make the heart need more oxygen, which can cause feelings of pain when the blood vessels cannot widen and supply the heart as they should. 

Unstable angina is when you experience symptoms during rest. It can worsen over time and, in some cases, can lead to a heart attack. 

What does angina feel like?

You may feel symptoms of angina in your chest, which may sometimes radiate to your left arm or jaw. Feelings may include:

• pain
• pressure
• tightness 
• heaviness

Other symptoms of angina include:

• nausea
• excessive sweating
• shortness of breath
• anxiety

If you experience angina symptoms, it’s important to seek immediate emergency medical attention to ensure your safety and well-being. 

Other medications for angina

There are some alternative medications that a doctor or healthcare professional may recommend for stable angina. A few examples are:

• Beta-blockers: These improve pain by decreasing heart rate and blood pressure. Options include:
  • atenolol (Tenormin)
  • metoprolol (Lopressor, Toprol)
  • nadolol (Corgard)
  • nebivolol (Bystolic)
  • propranolol (Inderal, InnoPran)
• Angiotensin-converting-enzyme (ACE) inhibitors: These medications can help manage blood pressure and reduce the risk of death from heart disease. Options include:
  • benazepril (Lotensin)
  • captopril (Capoten)
  • enalapril (Vasotec)
  • lisinopril (Qbrelis)
  • perindopril (Coversyl)
  • quinapril (Accupril)
  • ramipril (Altace)
  • trandolapril (Mavik)
  • quinapril (Acuprin)
• Angiotensin II receptor blockers (ARBs): Like ACE inhibitors, these medications control blood pressure and reduce the risk of severe heart disease complications. Options include:
  • azilsartan (Edarbi)
  • candesartan (Atacand)
  • irbesartan (Avapro)
  • losartan (Cozaar)
  • olmesartan (Benicar)
• Aspirin: These medications reduce the risk of complications like stroke. Options include Bufferin.
• HMG-CoA reductase inhibitors, also called statins: These drugs help reduce the risk of death from heart conditions and help improve cholesterol levels. Options include:
  • atorvastatin (Lipitor)
  • fluvastatin (Lescol XL)
  • lovastatin (Altoprev)
  • pitavastatin (Livalo)
  • pravastatin (Pravachol)

Lifestyle modifications

Besides medications, lifestyle changes can significantly improve heart health and help prevent angina. For example, you could try:

• stopping smoking if you smoke
• reducing cholesterol levels, blood pressure, and effectively managing blood sugar levels with a balanced diet
• getting to and maintaining an optimal body mass index.
• ensuring you get enough cardio exercise, aiming for at least 150 minutes of moderate intensity exercise or 75 minutes of high intensity exercise every week.

A healthcare professional can help you create the best treatment plan for your specific needs.

Summary

The medication nitroglycerin can relieve or prevent angina symptoms. A key way it works is by increasing blood flow to the heart muscle. 

Available forms include sprays, tablets, an IV drip, and patches. It can cause side effects, including headaches, fainting, nausea, and dizziness. 

Only take it if a healthcare professional prescribes it, and stick to the prescribed dosage. If your angina persists even after taking nitroglycerin, seek immediate emergency medical attention. 

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