What Are Opioids?

The opioid crisis in the United States has garnered a lot of attention over the past few years as one of the greatest public health threats in the country. Almost 400,000 people have died from opioid-related overdoses since 1999, and the drugs now kill more people than motor vehicle crashes in the country.

In response to the rapidly climbing number of overdose deaths due to opioids, the president of the United States declared the situation a national Public Health Emergency and urged federal departments working under the executive branch to do everything they can to stop the rising toll of opioids in communities throughout the United States.

So, what exactly are opioids? They are a collection of prescription pain relievers and street drugs that can affect how the body experiences pleasure and pain, lead to addiction, and—when misused—result in an overdose.

Vicodin pills
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Definition of Opioids

Opioids are a highly addictive group of drugs that bind to opioid receptors in the brain, blocking pain, producing euphoria, and causing the body to slow down.

Doctors will sometimes prescribe legal opioids as painkillers to treat people with moderate to severe pain, such as after an injury or while recovering from surgery. Others might misuse prescription opioids or use street versions (like heroin or illicitly-made fentanyl) to get high or sustain their addiction.

How Opioids Affect the Brain and Body

Opioids interfere with the pain and pleasure part of the body's nervous system, dialing down pain and often producing a sort of calming euphoria. It also slows down bodily processes, making people drowsy, slowing breathing, or affecting muscle control.

The effect opioids can have is sometimes overwhelming for the brain. So it adapts to dampen the effects.

The more you take opioids, the more you need to get the same level of pain relief or euphoria—a process called tolerance.

At the same time, the body can start to get used to the effect opioids have on it. It learns to expect the drugs and becomes reliant on them to function normally. When you stop taking the opioids, the body can have a rough time transitioning to working without them. Until it can fully adapt, you might experience withdrawal symptoms, such as flu-like symptoms, nausea, shakiness, or insomnia. This is called dependence.

After a certain point, taking opioids can no longer feel voluntary. It becomes a compulsion that negatively affects your personal and professional life, or becomes too difficult to control on your own. This is when many opioid users have developed an addiction to the drugs and may need professional help to stop taking them.

When someone misuses opioids—such as taking too many in a short period of time or mixing them with alcohol—it can result in an overdose, where breathing and heart rates slow down so much that it can deprive the brain of oxygen or result in death.

Opioids vs. Opiates

Historically, the term opioid was used to differentiate between synthetic or semi-synthetic opioids (like fentanyl or oxycodone) from opiates (like morphine), which are naturally derived from opium. Now, however, "opioid" is more often used as an umbrella term to describe any substance that binds to opioid receptors, regardless of how it is made.


Not all opioids are made the same way, and some are significantly more potent than others. Common examples of opioids include:

  • Oxycodone: A semi-synthetic opioid typically sold under the brand names OxyContin or Percocet.
  • Hydrocodone: Another semi-synthetic opioid that is sold under the brand name Vicodin.
  • Fentanyl: This is a powerful synthetic opioid that is 80 to 100 times more potent than morphine. Illegal versions of fentanyl and its analogs (like carfentanil, an elephant tranquilizer 10,000 times stronger than morphine) are believed to be a primary driver behind the recent spike in opioid-related overdose deaths.
  • Heroin: An illegal opioid made from morphine.
  • Codeine: A naturally-derived opioid pain reliever that is sometimes combined with non-opioid pain relievers like acetaminophen (or Tylenol).
  • Morphine: A painkiller made from opium.

A Word From Verywell

Not everyone who uses opioids will become addicted to them or overdose. Many people can use prescription opioid pain relievers safely when taking them for a short period of time and only as prescribed by their doctors. Some things can increase your chances of developing an addiction or overdosing on opioids including taking someone else's prescription, taking prescription painkillers more often or for longer than your doctor tells you to, mixing opioids with other drugs (including alcohol), or using street opioids like heroin.

If you or someone you care about show signs of being addicted to opioids, get help right away by talking to your doctor or calling the Substance Abuse and Mental Health Services Administration National Helpline: 1-800-662-HELP (4357).

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