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Fentanyl And Carfentanil

What Is The Difference Between Fentanyl And Carfentanil?

While fentanyl has been making headlines across North America for its incredibly damaging effects, a new name has come up that is even more frightening – carfentanil.

These two substances are being called the worst aggravators of the opioid crisis in Canada and the United States since it began. Hundreds of people have died through intended or accidental administration of these potent drugs, with thousands more becoming addicted every week.

But what exactly is the difference between fentanyl and carfentanil?

As their names might suggest, they are related in some way, but actually have some important differences with potentially deadly consequences. We explain everything you need to know about these two toxic substances below.

What are Fentanyl And Carfentanil?

To understand the differences between the two, we first need to understand what exactly fentanyl and carfentanil are. Fentanyl and carfentanil are synthetic opioid analgesics, or painkillers, that is incredibly potent. While they share a similar structure and method of action, there are important differences to make note of.


Fentanyl was first produced in 1960 by Paul Janssen and has been approved for use as a long term pain management medication in the United States and Canada since the late 60s. It works by binding extremely well to opioid receptors in the human body, blocking pain signals and allowing patients with debilitating chronic pain to have a higher quality of life. It is typically administered through transdermal skin patches, which can be discreetly applied to the skin to allow the medication to be absorbed into the bloodstream.

Fentanyl is occasionally preferred to other opioid painkillers such as morphine as it can avoid some of the more common side effects of these drugs like nausea, vomiting, sweating, cramps, and histamine-induced itching. Fentanyl is also approximately 100 times more potent than morphine requiring a significantly smaller dose to achieve the same level of pain management.


Carfentanil is an analogue of fentanyl that was developed in 1974 by the same chemists that created fentanyl. While fentanyl is approved for human use, carfentanil is strictly approved only for use in large mammals, such as elephants, tigers, and elk. It is used in tranquillizer darts and sedatives for these animals, as it is the most potent opioid known for non-human mammals and its relative safety margin for large animals is approximately the same as fentanyl. That means that an even smaller dose of carfentanil is required to achieve the same effects as fentanyl in larger mammals.

Carfentanil is approximately 10,000 times more potent than morphine, requiring even smaller doses than fentanyl to achieve the same results. However, as carfentanil is so potent, its use in humans becomes impractical as even a dose the size of a single grain of sand can be fatal. In the United States, there is a maximum yearly production limit of just 19 grams, showing you just how potent this drug is.

What Are They Used For?

Though fentanyl and carfentanil are analogues of each other, they are used for quite different things.

Fentanyl is primarily used in the management of long term pain in humans. Cancer patients and people suffering from progressive degenerative diseases such as multiple sclerosis can benefit the most from fentanyl, as it can be absorbed steadily throughout the day to provide long-lasting pain management.

Carfentanil is exclusively used as a tranquillizer for large mammals, such as bears and horses. Being 100 times more potent than fentanyl, the mammal that is being treated must have significantly more body mass than the average human being to not die from an average dose. There are no approved uses for carfentanil in humans, as even grazing a small grain of the drug with your skin can lead to death due to opioid overdose.

Is Fentanyl Or Carfentanil More Dangerous?

The ultimate question of which of these two drugs is more dangerous is a tricky one.

Fentanyl is 50 times more potent than heroin, producing an even greater high than the street drug. This makes it particularly attractive to opioid addicts, as they can use less of it to achieve even more potent results. However, because it is so potent, and the majority of fentanyl bought on the street is not given in exact doses, users never know exactly how much they might be taking. With a drug as powerful as fentanyl, a dose even just a few micrograms higher than expected could kill.

Many other street drugs such as cocaine and speed have been found to be cut with fentanyl. This presents another deadly chance for fentanyl to wreak havoc, as users believe they are getting one thing, when in fact they are getting another. This may cause them to take a huge dose without realizing it and go into respiratory arrest extremely quickly.

Carfentanil, on the other hand, is even more toxic than fentanyl, requiring an infinitesimally small dose to result in death. While this sounds like it might be even more desirable than fentanyl for drug users, its sheer potency makes using it safely impractical and more trouble than it would be worth for the stronger high. That being said, hundreds of kilograms of the drug have been found by police on the streets intended for sale, proving that there is likely a market out there for the drug.

Similarly to fentanyl, there is the risk of lacing other drugs with carfentanil to stretch out a dealer’s supply and potentially increase the addictiveness of the drugs. This would be even more dangerous than fentanyl lacing, and could easily cause death in a single dose.

Fentanyl & Carfentanil Drug Addiction Treatment

Like any opioid, the potential for abuse and addiction to fentanyl and carfentanil is extremely high. Many users quickly become addicted and begin suffering the adverse side effects of drug addiction, including weight loss, shortness of breath, apathy, loss of sex drive, antisocial behaviour, and potentially death.

Freedom from Addiction is one of Toronto’s leading drug addiction treatment centres specializing in fentanyl and carfentanil cases. Our compassionate and highly experienced medical professionals make it their top priority to help patients gradually wean themselves off opioids using a range of tried and tested methods.

Contact us today and find out how we can help you reclaim your life.


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