Nitrates can be used to prevent chest pain (angina), limit the number of angina attacks that you have, relieve the pain of a current attack, or treat the symptoms of heart failure. Nitroglycerin is a type of nitrate. How does it work?Nitrates are vasodilators, which means they help widen (dilate) your blood vessels, making it easier for blood to flow through and let more oxygen-rich blood reach your heart. Better blood flow means your heart doesn't have to work as hard. Nitrates also relax the veins so less blood is returned to the heart, which can reduce the workload on your heart. How should I take it?There are several different forms of nitrates:
Always talk to your doctor or pharmacist about how and when to take your specific medication. What should I avoid while taking this medicine?You should avoid smoking while you are taking nitrates since it may make them less effective. You should also avoid alcohol, because it may increase the effect of the medicine. What if I am taking other medicines?Nitrates can interact with other medications, so be sure to tell your doctor about any other medications you may be taking including prescription, non-prescription, over-the-counter or natural health products (vitamins and minerals, herbal remedies, homeopathic medicines, traditional medicines such as traditional Chinese medicines, probiotics and other products such as amino acids and essential fatty acids). Some medications that may cause an interaction include:
Speak to your doctor or pharmacist about any other information you may need to know about your medications. What else should I tell my doctor?Always give your doctor your complete medical history, especially if you are over 60 years of age, have recently had a stroke or heart attack or have severe headaches, low iron (anemia) or glaucoma. You may also want to talk to your doctor about how effective nitrates are for managing your angina. Your doctor can adjust the amount of medicine or suggest other ways of managing your condition. What are some side effects?Some common side effects of nitrates include headaches, flushing, dizziness, fainting, low blood pressure (hypotension) and irregular heart rhythms (arrhythmia). Report any and all side effects to your doctor. Lifestyle changesEating a healthy diet that is lower in fat, especially saturated and trans fats, being smoke free, limiting alcohol use, being physically active and reducing stress are also important in lowering the risk of heart disease. Talk to your healthcare practitioner about how you can achieve these lifestyle changes. Related informationHealth Canada - Drugs and Health Products provides health and medical information to help Canadians maintain and improve their health. Learn more about Drug Product Database provides information about drugs approved for use in Canada. MedEffect Canada provides safety alerts, public health advisories, warnings and recalls. Your ministry of health also provides useful health resources in your province or territory. For example, Ontario’s MedsCheck program provides free pharmacist consultations on safety use of drugs. And British Columbia’s Senior Healthcare webpage provides information about important health programs. Drug coverage Medically Reviewed by James Beckerman, MD, FACC on August 17, 2022 Do you know whether to take your nitroglycerin tablets before, during, or after chest pain? And are there times when you shouldn’t take it at all? Doctors usually prescribe nitroglycerin for angina pectoris, which often is called just "angina." It’s sudden heart-related chest pain. It happens because something prevents the flow of blood to your heart muscle. Nitroglycerin helps widen the blood vessels so more blood gets to your heart muscle. That helps stop the pain. Your doctor may give you instructions to take your nitroglycerin before you have angina. That means taking it before activities that are more likely to cause it. For example, you might take it 5 to 10 minutes before you go for a bike ride. You might also take it before: You may take your nitroglycerin when you first feel the symptoms of angina. It’s important to know your own body and what angina is like for you. You may have:
If you have angina, take your nitroglycerin as instructed by your doctor. This might mean you take it as soon as you feel symptoms, or you wait a minute before you take it, or you take more than one pill over several minutes. If you take your nitroglycerin as instructed and you still have chest pain, get medical help right away. As with any medicine, nitroglycerin might be harmful if you don’t take it correctly. You should not take nitroglycerin if:
Men with heart disease and other long-term health problems are more likely to have erectile dysfunction (ED) or trouble with erections. There are medicines that help men who have ED. You or your partner may take one of them. Prescription ED pills include: Why shouldn’t you take your ED medicine with your nitroglycerin? The reason is that both lower your blood pressure. Taken together, your blood pressure may get to a very low, and dangerous, level. Because of this effect, the American Heart Association warns against it. You may still be able to take both medicines, at different times. Talk with your doctor about how long you should wait between taking the two medicines. For example, you may have to allow 24 to 48 hours or more between taking your ED medicine and nitroglycerin When something restricts blood flow to the heart muscle, a person may experience intense chest pain that doctors call angina. People can use the drug nitroglycerin to relieve this pain. Most often, the reason for this decrease in blood flow is plaque formation and the narrowing of the arteries supplying blood to the heart. Nitroglycerin helps open up the blood vessels and allows blood to flow. People can also use nitroglycerin to treat anal fissures. This article provides an overview of nitroglycerin, including its uses, how it works, possible side effects, interactions, and warnings.
Nitroglycerin is a medication that treats angina and 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 1–3 minutes, but its maximal effect occurs after 5 minutes. Different forms of the medication start working at different time periods, depending on their formulation. For example:
The medication’s maximal effect also depends on its formation. For example:
When people use nitroglycerin for anal fissures, the ointment will relax the anal sphincter, which is the muscle tissue around the anus, and lower pressure in the anus. This promotes blood flow to the area and helps the fissure heal. Doctors usually use nitroglycerin to treat the pain associated with angina. The narrowing of the arteries that supply the heart with blood is what causes unstable angina. Doctors call this condition coronary artery disease (CAD). CAD is the most common type of heart disease. Almost 366,000 people in the United States die every year because of CAD. Nitroglycerin allows the blood vessels to open up, letting 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 develop anal fissures from passing hard stools. Similar to its effects on 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. AnginaWhen someone is experiencing intense chest pain, it is vital to resolve this symptom as quickly as possible. People can also take fast-acting nitroglycerin formulations 5–10 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. The following sections look at these forms in more detail. Aerosol spray and pumpsprayPeople can use these devices by giving one or two sprays on or under the tongue once they feel angina pain. They should not inhale the spray. PacketA sublingual packet of nitroglycerin contains 400 micrograms of nitroglycerin powder. A person places the contents of the packet under their tongue when angina pains begin. TabletAt the first sign of angina pain, 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 on its own. This provides faster relief than swallowing the medication. 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 a fast-acting formulation and does not experience any pain relief, they need medical attention immediately. There are also two other formulations of nitroglycerin that can prevent angina attacks. These are not fast-acting, so people should not use them to stop an attack when it is happening. PatchNitroglycerin 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 their skin for 12–14 hours and remove it for 10–12 hours. People usually have the patch on during the day and remove it during sleep. OintmentPeople can apply nitroglycerin ointment to their skin using a dose-measuring applicator that comes with the tube. A person measures the desired dose onto the measuring applicator and then places the applicator ointment side down on the skin. They then spread the ointment across the skin. The person should not rub the medication in but allow the ointment to absorb across the skin. Finally, they tape the applicator to the skin. People apply two doses of ointment each day. Doctors usually tell people to use the ointment first thing in the morning and reapply it 6 hours later. Anal fissuresThe rectal ointment for anal fissures contains 0.4% nitroglycerin. A person inserts the ointment into their anus every 12 hours for up to 4 weeks. If symptoms persist, a person may take the medication for another 4 weeks, totaling 8 weeks. To apply the rectal ointment, a person covers their finger with plastic wrap and puts 1 inch of ointment along the finger. They then insert the finger into the anal canal up to the first finger joint. The person then smears 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 use nitroglycerin for relieving angina, they should be in a relaxed, seated position. A person’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 a headache, but this side effect decreases with medication use. Although people only apply rectal ointment to the anus, they may still experience headaches and dizziness. Some people may have allergies to nitroglycerin, so doctors do not recommend that people use it if they have a history of allergic reactions to this medication. Doctors do not prescribe nitroglycerin to anyone with a history of severe anemia, heart attack occurring on the right side of the heart, or increased pressure in the brain. ContraindicationsNitroglycerin contraindications include allergic reactions, though these reactions are rare. Other contraindications include: Nitroglycerin may interact with certain other medications, such as PDE-5 inhibitors. PDE-5 inhibitors are drugs that doctors give to treat erectile dysfunction. 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 these medications can cause fainting if someone is taking them together. People should avoid using nitroglycerin if they have taken Viagra or Levitra within the past 24 hours or Cialis within the past 48 hours. Anyone using long-acting nitroglycerin cannot take PDE-5 inhibitors. The nitroglycerin dosage may be different for different people. For example, the dosage may depend on the form of the drug a person is using. It can also change based on:
Generic nitroglycerin comes in the form of a sublingual tablet. The strengths of these tablets are 0.3 mg, 0.4 mg, and 0.6 mg. Brand-name nitroglycerin, Nitrostat, comes in the form of a sublingual tablet. The strengths of this tablet are 0.3 mg, 0.4 mg, and 0.6 mg. An overdose of nitroglycerin may occur when a person uses PDE-5 inhibitors with nitroglycerin or uses too much nitroglycerin during an angina attack. Severe side effects that doctors associate with a nitroglycerin overdose include:
Currently, no drug can reverse a nitroglycerin overdose. That said, doctors can provide care to people experiencing an overdose by giving them intravenous fluids and elevating their legs. Using nitroglycerin in the appropriate way can delay the serious complications of angina, which include heart attack, stroke, and even death. People may experience side effects with nitroglycerin, so they should remain seated while the drug takes effect. Nitroglycerin can interact with erectile dysfunction medications. People with angina should report the use of Viagra, Cialis, and Levitra to a doctor because using both drugs together may be dangerous. People can also treat anal fissures using nitroglycerin rectal ointment. Side effects and interactions can also occur with the topical use of nitroglycerin. |