
Whenever your health care provider prescribes a medicine, it’s important to learn about the drug you’ll be taking. In this short guide, we’ll discuss different types of opioids. For more information about opioids, read the Mayo Clinic Press Book “Ending the Crisis: Mayo Clinic’s Guide to Opioid Addiction and Safe Opioid Use.”
What are opioids prescribed for?
Prescription opioids are used to treat moderate to severe pain. Opioids are generally classified for either acute or chronic use.
- Acute use refers to short-term use, typically a few hours or days. For example, you may be prescribed opioids for a short time after a surgery.
- Chronic use refers to taking opioids for more than 45 to 90 days on a near-daily basis. You may be prescribed opioids long term to control pain caused by advanced-stage cancer.
How do opioids work?
Opioids primarily reduce pain by interrupting central nervous system signals between the brain and the body. When opioids enter the bloodstream, they work their way toward nerve cells and attach themselves to opioid receptors (anchoring points on the surface of the cells). When opioids bind to these receptors, they trigger a series of chemical reactions — blocking pain signals.
How many different opioids exist?
There are around 10 to 12 opioids used routinely in clinical settings today. Some opioids such as heroin have no medical purposes and can only be obtained from illicit sources like the streets. Similarly, fentanyl has received considerable national attention for being the No. 1 cause of opioid-related overdose deaths when obtained through illicit means.
What opioids do doctors prescribe?
Doctors prescribe different opioids in different circumstances. Here is an opioids list based on the level of pain.
Moderate to severe acute pain
- Codeine.
- Morphine.
- Hydromorphone (Dilaudid).
- Hydrocodone and acetaminophen.
- Oxycodone (Oxaydo, Roxicodone, Roxybond).
- Oxycodone and acetaminophen (Percocet).
Chronic pain
- Buprenorphine (Belbuca, Butrans).
- Methadone (Methadone HCl Intensol).
- Hydrocodone extended release (Hysingla ER).
- Morphine extended release (MS Contin).
- Tapentadol extended release (Nucynta ER).
- Oxycodone extended release (OxyContin, Xtampza ER).
Are opioids legal?
When used as part of medical care, opioids are legal. However, opioids are controlled substances. This means they’re federally regulated and can only be prescribed or administered by people who have a license to do so — such as a doctor or pharmacist. Many opioids now available on the streets have no legitimate medical purposes and are considered illegal by the federal government. Examples include heroin and a number of novel compounds that resemble heroin.
What are the different types of opioids?
Chemists, pharmacologists and medical professionals have several ways to classify opioids, but the easiest distinction is around how opioids are made. Opioids are made in three main ways:
- Natural opioids. These opioids are made from the opium poppy plant. They include morphine, opium and heroin.
- Synthetic opioids. Created in a laboratory and completely developed through chemical processes, this category of opioids includes fentanyl and methadone.
- Semi-synthetic opioids. Opioids such as oxycodone, hydrocodone and hydromorphone are made from opium plants that have been chemically changed from the original poppy plant.
Opioids are also categorized by frequency, or how often doses are necessary:
- Long-acting opioids. Prescribed for people who expect to have long-term pain, such as cancer pain, extended-release (ER) or sustained-release (SR) medicines stay in the bloodstream at a steady concentration for longer periods of time.
- Short-acting opioids. Immediate-release opioids only stay in the bloodstream for short periods. They’re often used for short-term treatment of moderate to severe pain, such as after an injury or a surgery.
How are opioid medications administered?
An opioid can enter the body in many ways, also known as routes. Examples include ingesting (swallowing), injecting, inhaling or using a transdermal form (a patch). Each route has different effects. The route chosen depends on the opioid medicine used, the patient’s condition, the length of treatment and the level of pain.
What opioid is causing the most deaths?
Fentanyl, a synthetic opioid, is 50 to 100 times more powerful than morphine. Pharmaceutical fentanyl was originally developed to manage pain in cancer patients. However, illicitly manufactured fentanyl is sold on its own or combined with other drugs, such as heroin, cocaine or methamphetamine. As a result, provisional data showed that fentanyl (along with other synthetic opioids) was responsible for more than 71,000 deaths in 2021 alone.
A version of this text appears in the Mayo Clinic Press Book “Ending the Crisis: Mayo Clinic’s Guide to Opioid Addiction and Safe Opioid Use.”

Relevant reading
Ending the Crisis
An authoritative guide to understanding the current opioid crisis in America and how it can be solved.
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