Caption: Estimated lethal doses for the most common opioids based on relative potency. These doses correspond to the weight of drug that can be lethal for a patient who has not taken opioids in the past. The lethal doses can be much higher for patients who are currently taking opiods. The comparisons with the objects on the right are made based on weight.

What are Opioids

Morphine, an opioid, has been used for centuries to relieve pain for patients.

Opioids are a naturally occurring compound found in plants. They are also part of a key neurochemical system in our body that naturally regulates pain and other feelings.

Endorphins, the endogenous compounds responsible for the "Runner's High," are opioids produced by your own body.

Opioids are an essential medication. When used responsibly, they are an essential tool for treating a patient's pain.

Unfortunately, they are also very addictive.

Synthetic Opioids

Synthetic opioids are compounds that were designed and synthesized in laboratories to be significantly stronger than heroin or morphine. These bind tighter and longer to opioid receptors than morphine or other naturally occurring opioids.

These are needed as patients on opioids chronically quickly accustomed to their dose. Patients who take opioids often need increasingly higher doses of opioids to provide the same levels of pain relief.

Fentanyl, one of the most common synthetic opioids, was initially approved for patients with chronic or terminal illnesses for whom morphine or other opioids no longer worked. Fentanyl has been estimated at 80-100x more potent than morphine.

This provides much needed relief for cancer patients in the hospital. But it has also driven much of the opioid crisis given its high potency. The NIH has estimated that fentanyl is one of the leading drivers of drug overdose deaths in the United States.

The Newest Synthetic Opioids

The newest generations of opioids are even more potent than fentanyl. Sufentanil, which was just approved by the FDA, has been estimated at 10x more potent than fentanyl. This drug is intended only for hospital patients, but it has generated some controversy given its very high potency.

Carfentanil, the last drug on the list above, has not been approved by the FDA. It is only approved for veterinary uses. However, it is often smuggled and illegally imported into the United States. Only a tiny amount of this, amounting to a couple of milligrams, can kill an individual not accustomed to opioids.