Cinnamon is a spice made from the inner bark of the Cinnamomum tree.
It is widely popular and has been linked to some impressive health benefits, including a lower risk of diabetes, cancer and heart disease (, ).
The two main types of cinnamon are:
- Cassia: 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. This is 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 (, 4, ).
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.
Cassia or “regular” cinnamon is a rich source of coumarin.
It contains approximately 5 mg of coumarin per teaspoon (2 grams), while Ceylon cinnamon only contains trace amounts of it (6).
The recommended daily coumarin limit is approximately 0.05 mg/pound (0.1 mg/kg) of body weight, or 5 mg per day for a 130-pound (60-kg) person. This means that just one to one and a half teaspoons of Cassia cinnamon could put you over the daily limit.
Unfortunately, several studies have found that eating too much coumarin may cause liver toxicity and damage (, 4, ).
For example, a 73-year-old woman developed a sudden liver infection causing liver damage after taking cinnamon supplements for only one week (). 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.
Animal studies have shown that eating too much coumarin, which is abundant in Cassia cinnamon, may increase the risk of certain cancers ().
The way in which coumarin may cause tumors is unclear.
However, some scientists believe that coumarin may damage certain organs repeatedly. Over time, the damage may cause healthy cells to be replaced by tumor cells, which may become cancerous (11).
Most research on the cancerous effects of coumarin has been performed on animals, and 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.
Some people have experienced mouth sores from eating too much cinnamon (, 13, ).
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 and white patches in the mouth. While these symptoms aren’t necessarily serious, they can cause discomfort ().
However, it’s important to note that cinnamaldehyde will only cause mouth sores if you are allergic to it. You can get tested for this type of allergy with a skin patch test ().
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.
Having chronic high blood sugar is a health problem. If left untreated, it may lead to diabetes, heart disease and many other health problems ().
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, and it can lead to tiredness, dizziness and possibly fainting ().
People who are most at risk of experiencing low blood sugar are those taking medicines for diabetes. This is because cinnamon may enhance the effects of these medicines 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.
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 and make it hard to catch your breath.
Also, the cinnamaldehyde in cinnamon is a throat irritant and 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.
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 medicines, 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 (, 4, ).
If you are taking medicines that may affect your liver, such as paracetamol, acetaminophen and statins, too much cinnamon may increase the chance of liver damage ().
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.
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 ().
While it may sound harmless, the challenge can be very dangerous.
Eating dry cinnamon can irritate your throat and lungs. It can also make you gag, choke or permanently damage your lungs.
This is because the lungs cannot break down the fibers in the spice. This means it may accumulate in the lungs and cause lung inflammation known as aspiration pneumonia (, ).
If aspiration pneumonia is left untreated, the lungs may become permanently scarred and possibly collapse ().
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.
Cinnamon is generally safe to eat and linked to many impressive health benefits.
However, eating too much may cause potentially dangerous side effects.
This mostly applies to Cassia cinnamon because it is a rich source of coumarin. Conversely, Ceylon cinnamon contains only trace amounts of coumarin.
In fact, research has found that Cassia, on average, contains 63 times more coumarin than Ceylon (6).
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 ().
This equates up to one teaspoon (0.5 to 2 grams) of Cassia cinnamon per day. However, you can eat up to 2.5 teaspoons (5 grams) of Ceylon per day.
Keep in mind that these amounts are for adults and children can tolerate less.
Summary You can safely eat up to one teaspoon of Cassia cinnamon or up to 2.5 teaspoons of Ceylon cinnamon per day. Eating more than this is not advised, as it may contain too much coumarin.
Cinnamon is a delicious spice, linked to many health benefits.
While eating small to moderate amounts is safe, eating too much may cause side effects. This mostly applies to Cassia or “regular” cinnamon because it contains high amounts of coumarin, which has been linked to conditions like liver damage and cancer.
On the other hand, Ceylon or “true” cinnamon only contains trace amounts of coumarin and can be safely consumed in larger amounts.
You can safely eat up to one teaspoon (0.5 to 2 grams) of Cassia cinnamon or up to two and a half teaspoons (5 grams) of the Ceylon type per day.
While eating too much cinnamon may have some drawbacks, it’s a healthy spice that’s safe to eat in small to moderate amounts. Eating less than the tolerable daily intake is more than enough to provide you with its health benefits.