Opioids are a class of medication that doctors may prescribe to treat severe or persistent pain. However, opioids that people may use illegally, such as heroin, also exist.

Opioids may help people find relief from severe or persistent pain. Doctors typically prescribe them for short-term care, and they will help monitor a person’s opioid use due to possible side effects, including physical dependency and tolerance.

However, people do not always use opioids as a doctor prescribes or for medicinal purposes. For example, many know heroin is an illegal opioid that some individuals use recreationally.

This article reviews the different types of prescription opioids, illegal opioids, how opioids differ from opiates, and when to speak with a doctor.

A pill which may be a prescription opioid resting on a person's palm 1Share on Pinterest
Ekaterina Zaitseva/Getty Images

Doctors prescribe opioids to treat moderate or severe pain. According to the Centers for Disease Control and Prevention (CDC), a healthcare professional may prescribe them for:

  • recovery from major surgery
  • advanced stages of cancer
  • a serious injury

In some cases, a doctor may prescribe opioids for conditions that cause chronic pain, such as osteoarthritis. However, prescribing them for these conditions is controversial due to serious health risks and a lack of evidence about their long-term efficacy.

Therefore, people need to speak with their doctor about the potential risks and side effects of opioids.

Risks and side effects

While opioids may offer relief to individuals who have not experienced relief from other therapies, they come with several risks. These include:

Even at safe doses, they can cause side effects that may include:

Opioids are a type of controlled substance. The Drug Enforcement Administration (DEA) places additional controls over certain substances due to their potential for addiction and misuse. The agency classes many prescription opioids as Schedule 2 drugs, meaning they have a high potential for abuse.

Doctors often calculate the morphine milligram equivalent when determining which opioid to prescribe. This measure represents an opioid’s potency relative to morphine. It is important when changing a patient’s opioid regimen to minimize the risk of side effects and ensure safe dosing.

As with any medication, if a doctor prescribes a person a Schedule 2 opioid, they should follow the doctor’s advice when taking it.


Some common examples of prescription opioids in the United States include:

Opioid nameForms
codeinetablet, capsule, and liquid
methadonetablet, dispersible tablet, and liquid
hydrocodone or dihydrocodeinonecapsule, liquid, and tablet
hydromorphoneliquid and suppository
meperidinetablet and liquid
fentanyllozenge, sublingual tablet, film, and buccal tablet
morphinetablet, liquid, capsule, and suppository
oxycodonecapsule, liquid, and tablet

Some types of opioids, such as heroin, have no known medical use and are therefore illegal in the U.S. as Schedule 2 drugs under the DEA. While people make them specifically for recreational use, some also use prescription opioids illegally.

In addition to the potential for a fatal overdose and addiction, using illegal opioids may lead to health issues that include:

Heroin is a prime example of an illegal opioid, but several other prescription opioids are well-known for illegal misuse, including:

  • fentanyl
  • oxycodone
  • hydrocodone
  • codeine
  • morphine
  • methadone

People may use the terms “opioids” and “opiates” to refer to the group of drugs. However, they are not the same. As a result, individuals often blend the terms and use them interchangeably.

Opiates come from plant-based materials, such as poppy fibers and sap. Examples include:

  • heroin
  • morphine
  • opium
  • codeine

However, the term “opioids” refers to all opiates, including semisynthetic and synthetic opioids, which people typically make in laboratories. Examples of synthetic and semisynthetic opioids include:

  • fentanyl
  • methadone
  • oxycodone
  • hydrocodone

Opioids can cause several different side effects as well as a risk of addiction or dependency. Therefore, a person should consider contacting a doctor if they are concerned about any side effects they are experiencing from them. A doctor may be able to provide additional treatments to help or recommend a different therapy for pain.

Some people can develop opioid use disorder while taking prescription opioids. This disorder may cause an overpowering desire to use opioids despite experiencing adverse consequences. It may also lead to increased opioid tolerance and withdrawal syndrome when the person stops using opioids.

People who use prescription opioids are also at risk of experiencing an opioid overdose. Healthcare professionals primarily use naloxone to treat opioid overdose.

The CDC notes that many overdose cases relating to opioid use involved the additional use of benzodiazepines. People should avoid taking opioids in combination with benzodiazepines, such as:

A person should speak with a doctor for further information before taking any medications to learn more about the potential risks and side effects. People with opioid use disorder should also speak with a healthcare professional for treatment and support.

Help is available

Seeking help for addiction may feel daunting or even scary, but several organizations can provide support.

If you believe that you or someone close to you is showing signs of addiction, you can contact the following organizations for immediate help and advice:

Was this helpful?

Opioids are a type of drug doctors typically prescribe to relieve pain. However, people also manufacture them for illegal use.

Though prescription opioids may help individuals with moderate to severe pain, they can also cause various side effects. They also have a risk of causing dependency and addiction in people who use them, particularly for long periods. A person should speak with a doctor about the risks and side effects of opioids.

People who take prescription opioids are also at risk of overdose. A person should discuss other medications they are taking with a doctor, as they may increase the risk of overdose.