Lesson 1: What are opioids?

Lesson Goal


For you to understand the basics about the main types of opioid drugs, opioid addiction and types of treatments available.

Lesson Summary


The term “opioid” includes multiple drugs in multiple forms: naturally derived opioids (such as morphine and codeine), semi-synthetic opioids (like hydrocodone), and fully synthetic opioids (like Fentanyl). Opioids relieve pain by binding to receptors in the brain, and they also trigger the release of dopamine and create a sense of euphoria. The potency of different opioids in terms of ability to relieve pain is measured using a number called the Morphine Milligram Equivalent (MME).

The Big Topics in This Lesson


1- Understanding What Drugs Are Involved In the Crisis

The information under this topic covers basic information about the drugs at the heart of the crisis.

2- Understanding How Opioids Work

The information under this topic explains how opioids relieve pain and cause addiction.

3- Understanding Morphine Milligram Equivalents (MMEs)

The information under this topic explains how researchers and clinicians use MMEs to standardize the estimate of potency across opioids.

Lesson Video


Lesson Q & A


Click on each question to learn more

Q1: What are opioids?



Opioid drugs are drugs made to reduce pain by imitating the properties of opium. (The word “opioid” can be understood as “like opium”). There are legal drugs and illegal drugs in the opioid category. Some examples of legal opioids include oxycodone, hydrocodone, and morphine.

The legal opioids are usually prescribed for chronic pain or to relieve acute pain following an injury or procedure. Because opioids also create a sense of euphoria (a “high”), legal opioids are also abused as recreational drugs, even when they are obtained legally.

Illegal opioids such as heroin have a long history of abuse and addiction.

Opioids fall into 3 main categories:

  1. Naturally derived opioids
  2. Semi-synthetic opioids
  3. Fully-synthetic opioids


Opium “latex” leaking from the opium plant

Naturally derived opioids (Opioids made from opium poppy plants)

Morphine and codeine are naturally derived from opium plants. The opium plants are grown in fields as part of large drug-trade operations in Asia, South America and Central America.

Heroin is synthesized using morphine, so it is typically grouped with the naturally-derived opioids instead of the semi-synthetic opioids.


An opium field in Afghanistan


Semi-synthetic opioids

This group includes hydrocodone and oxycodone. These drugs are made in labs combining natural and synthetic ingredients. One of the most well-known drugs in this group is Vicodin (the brand name of hydrocodone). More than 6.2B hydrocodone pills were dispensed in the U.S. in 2016 alone. Percocet (one of the brand names for oxycodone, another is Oxycontin) came in a close second, with 5B tablets placed in the U.S. population in the same year.


Fully synthetic opioids

This group includes things like Fentanyl and Methadone. They are made in labs using synthetic ingredients. Most of the deaths seen in the recent years of the crisis are from Fentanyl.

  • Methadone is used to assist recovering heroin addicts by lessening withdrawal symptoms.
  • Fentanyl was originally made to help sever pain following surgery and to assist cancer patients with severe pain. It is 100 times more powerful than morphine, and only a small dose is needed to be fatal. This drug has been a large factor in the increase in overdose deaths in recent years.

Select Opioid Profiles


Oxycodone 5 mg tablet

Oxycodone is the most widely abused recreational opioid. According to US HHS, there are 11M Americans who use it (in a non-medical way) each year.




Fentanyl is a synthetic opioid made in labs. It is 20 to 30 times stronger than heroin (and 50 to 100 times stronger than morphine). Fentanyl is driving the surge in overdose deaths, with Fentanyl-related deaths rising by 540% since 2015. It is sometimes added to heroin, or made into pills.


It only takes 2 mg to die from an overdose. Even touching it can be dangerous, and first responders such as police officers and EMTs have overdosed just by coming in contact with it. Often times addicts think they are using heroin and it is in fact Fentanyl. This confusion increases the risk of overdose, since they are using a much more powerful drug than they think they are. Sometimes Fentanyl is pressed into pills and colored to look like oxycodone, which also greatly increases the risk of overdose since the user is expecting a much weaker opioid than Fentanyl.


The profitably of illegal Fentanyl sales is high for Mexican drug cartels. One kilogram can be bought in China for $3,000 and then smuggled into the United States and sold for $1.5M (500 times the cost).

Q2: How do opioids work?


Opioids relieve pain by binding to receptors in the brain and spine that are used to communicate pain signals. The opioids block or disrupt these signals.

In addition to blocking pain, opioids also trigger the brain to release a hormone called dopamine. This hormone is used by the body to create a sense of “euphoria.”

Q3: What are Morphine Milligram Equivalents (MMEs)?


Since morphine is recognized as the “gold standard” for treatment of pain, and opioids are all of different strengths, the standard unit used to compare the strength of different opioids is the Morphine Milligram Equivalent, or MME. 1 MME is defined as the analgesic (pain relieving) effect of 1 mg of Morphine.



Medicaid Dictionary

 New Terms from this lesson:
  1. Morphine Milligram Equivalent (MME)- a number that measures potency of different opioids in terms of ability to relieve pain compared to morphine.
  2. Semi-synthetic drugs– drugs are made in labs combining natural and synthetic ingredients.
  3. Dopamine– Dopamine is a brain neurotransmitter that helps regulate emotional responses. It contributes to feelings of pleasures and satisfaction as part of the reward system. This neurotransmitter plays a large role in addiction.

Ready for the Lesson Progress Quiz?


When you are ready to take the quiz, click the button below. You must pass the quiz to move onto the next lesson.

Back to: Understanding the Opioid Crisis- Part 1 > Course Lessons