Cinnamon is a spice made from the inner bark of the Cinnamomum tree. It’s widely popular and has been linked with health benefits like improved blood sugar control and lowering of some risk factors for heart disease (1, 2 ). The two main types of cinnamon are: Cassia: Also called “regular” cinnamon, this is the most commonly used type.

Also called “regular” cinnamon, this is the most commonly used type. Ceylon: Known as “true” cinnamon, Ceylon has a lighter and less bitter taste. Cassia cinnamon is more commonly found in supermarkets, given that it’s much cheaper than Ceylon cinnamon. While Cassia cinnamon is safe to eat in small to moderate amounts, eating too much may cause health problems because it contains high amounts of a compound called coumarin. Research has found that eating too much coumarin may harm your liver and increase the risk of cancer ( 3 , 4, 5 ). Furthermore, eating too much Cassia cinnamon has been linked to many other side effects. Here are 6 possible side effects of eating too much Cassia cinnamon.

1. May Cause Liver Damage Share on Pinterest Cassia (or regular) cinnamon is a rich source of coumarin. The coumarin content of ground Cassia cinnamon may range from 7 to 18 milligrams per teaspoon (2.6 grams), while Ceylon cinnamon only contains trace amounts of coumarin (6). The tolerable daily intake of coumarin is approximately 0.05 mg/pound (0.1 mg/kg) of body weight, or 5 mg per day for a 130-pound (59-kg) person. This means that just 1 teaspoon of Cassia cinnamon could put you over the daily limit ( 3 ). Unfortunately, several studies have found that eating too much coumarin may cause liver toxicity and damage (4, 5 ). For example, a 73-year-old woman developed a sudden liver infection causing liver damage after taking cinnamon supplements for only 1 week ( 7 ). However, this case involved supplements that provided a higher dose than you would get from diet alone. Summary Regular cinnamon contains high amounts of coumarin. Studies have shown that eating too much coumarin may increase the risk of liver toxicity and damage.

2. May Increase the Risk of Cancer Animal studies have shown that eating too much coumarin, which is abundant in Cassia cinnamon, may increase the risk of certain cancers ( 3 ). For example, studies in rodents have found that eating too much coumarin can cause cancerous tumors to develop in the lungs, liver, and kidneys (8, 9, 10 ). The way in which coumarin may cause tumors is unclear. However, some scientists believe that coumarin causes DNA damage over time, increasing the risk of cancer (11). Most research on the cancerous effects of coumarin has been performed on animals. More human-based research is needed to see if the same link between cancer and coumarin applies to humans. Summary Animal studies have found that coumarin may increase the risk of certain cancers. However, more research is needed to determine whether this also applies to humans.

3. May Cause Mouth Sores Some people have experienced mouth sores from eating products that contain cinnamon flavoring agents (12, 13 , 14 ). Cinnamon contains cinnamaldehyde, a compound that may trigger an allergic reaction when consumed in large amounts. Small amounts of the spice don’t seem to cause this reaction, as saliva prevents chemicals from staying in contact with the mouth for too long. In addition to mouth sores, other symptoms of a cinnamaldehyde allergy include: tongue or gum swelling

a burning or itching sensation

white patches in the mouth While these symptoms aren’t necessarily serious, they can cause discomfort ( 14 ). However, it’s important to note that cinnamaldehyde will only cause mouth sores if you’re allergic to it. You can get tested for this type of allergy with a skin patch test ( 15 ). Also, mouth sores seem to mostly affect those who use too much cinnamon oil and cinnamon-flavored chewing gums, as these products can contain more cinnamaldehyde. Summary Some people are allergic to a compound in cinnamon called cinnamaldehyde, which can cause mouth sores. However, this seems to mostly affect people who use too much cinnamon oil or chewing gum, as these products contain more cinnamaldehyde.

4. May Cause Low Blood Sugar Having chronic high blood sugar is a health problem. If left untreated, it may lead to diabetes, heart disease, and many other health problems (16). Cinnamon is well-known for its ability to lower blood sugar. Studies have found that the spice can mimic the effects of insulin, a hormone that helps remove sugar from the blood ( 17 , 18 , 19 ). While eating a bit of cinnamon may help lower your blood sugar, eating too much may cause it to fall too low. This is called hypoglycemia. It can lead to tiredness, dizziness, and possibly fainting ( 20 ). People who are most at risk of experiencing low blood sugar are those taking medications for diabetes. This is because cinnamon may enhance the effects of these medications and cause your blood sugar to fall too low. Summary While eating cinnamon may help lower your blood sugar, eating too much may cause it to fall too low, especially if you’re on medication for diabetes. Common symptoms of low blood sugar are tiredness, dizziness, and fainting.

5. May Cause Breathing Problems Eating too much ground cinnamon in a single sitting may cause breathing problems. This is because the spice has a fine texture that can make it easy to inhale. Accidentally inhaling it can cause: coughing

gagging

difficulty when trying to catch your breath Also, the cinnamaldehyde in cinnamon is a throat irritant. It may cause further breathing problems (21). People with asthma or other medical conditions that affect breathing need to be especially careful of accidentally inhaling cinnamon, as they are more likely to experience trouble breathing. Summary Eating too much ground cinnamon in a single sitting may cause breathing problems. The fine texture of the spice makes it easy to inhale and irritate the throat, which may cause coughing, gagging, and trouble catching your breath.

6. May Interact with Certain Medications Cinnamon is safe to eat in small to moderate amounts with most medications. However, taking too much may be an issue if you’re taking medication for diabetes, heart disease, or liver disease. This is because cinnamon may interact with those medications, either enhancing their effects or intensifying their side effects. For example, Cassia cinnamon contains high amounts of coumarin, which can cause liver toxicity and damage if consumed in high amounts ( 3 , 4, 5 ). If you’re taking medications that may affect your liver, such as paracetamol, acetaminophen, and statins, excessive intake of cinnamon may increase the chance of liver damage ( 7 ). Also, cinnamon may help lower your blood sugar, so if you’re taking medications for diabetes, the spice may enhance their effects and cause your blood sugar to fall too low. Summary If eaten in large amounts, cinnamon may interact with medications for diabetes, heart disease, and liver disease. It may either enhance their effects or increase their side effects.

Risks of Eating Dry Cinnamon Since the “cinnamon challenge” has become wildly popular, many have attempted to eat large amounts of dry cinnamon. This challenge involves eating a tablespoon of dry, ground cinnamon in under a minute without drinking water (22). While it may sound harmless, the challenge can be very dangerous. Eating dry cinnamon can irritate your throat and lungs, as well as make you gag or choke. It can also permanently damage your lungs. This is because the lungs cannot break down the fibers in the spice. It may accumulate in the lungs and cause lung inflammation known as aspiration pneumonia (23, 24 ). If aspiration pneumonia is left untreated, the lungs may become permanently scarred and possibly collapse ( 24 ). Summary While eating large amounts of dry cinnamon might seem harmless, it can be very dangerous. If cinnamon reaches your lungs, it can’t be broken down and may cause an infection and permanent lung damage.

How Much Is Too Much? Cinnamon is generally safe to use in small amounts as a spice. It’s linked to many impressive health benefits. However, eating too much may cause potentially dangerous side effects. This mostly applies to Cassia cinnamon because it’s a rich source of coumarin. Conversely, Ceylon cinnamon contains only trace amounts of coumarin. The tolerable daily intake for coumarin is 0.05 mg per pound (0.1 mg per kg) of body weight. This is how much coumarin you can eat in a day without the risk of side effects ( 3 ). This equates up to 8 mg of coumarin per day for an adult weighing 178 pounds (81 kilograms). For reference, the amount of coumarin in 1 teaspoon (2.5 grams) of ground Cassia cinnamon ranges from 7 to 18 mg (6). Keep in mind that children may tolerate even less. Although Ceylon cinnamon contains only trace amounts of coumarin, excessive intake should be avoided. Cinnamon contains numerous other plant compounds that may have adverse effects when consumed in high amounts. Use all cinnamon sparingly as a spice. Summary Adults should avoid eating more than 1 teaspoon of Cassia cinnamon per day. Children may tolerate even less.