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Opioids, also called narcotics, are a class of drugs that work to relieve pain.

A doctor may prescribe opioids to help treat symptoms like:

Any opioid use can sometimes cause unwanted side effects, including nausea, constipation, drowsiness, confusion, and slowed breathing. You may have a higher risk of side effects if you:

  • take a higher dose than prescribed by your doctor
  • take them more frequently or for a longer period of time than your doctor prescribed
  • take them without a prescription
  • combine them with alcohol, sleeping pills, or certain other drugs

Opioid use may also increase your chances of experiencing:

  • Tolerance: If you’ve developed a tolerance to opioids, you need to use more to notice the same effect.
  • Dependence: This means your body has grown used to the opioids in your system. When you stop taking them, you’ll experience symptoms of withdrawal.
  • Opioid use disorder (OUD): You may have OUD if you feel unable to stop taking opioids even when you try, or keep taking them even though they have unwanted effects on your health or personal life.
  • Opioid overdose: This can happen when you take a larger dose of opioids than your body can safely handle. Opioid overdose can be fatal.

Opioids have important medical uses, but using them, especially long term, may pose some risks. Read on to learn about the different types of opioids, how they affect your body, and which side effects to pay attention to.

Opioids come in many forms, some much more potent than others.

The three main classes of opioids include:

Natural opioids

Also called opiates, natural opioids come from the seed pods of the poppy plant Papaver somniferum. More specifically, they’re derived from the coating around the seeds. The poppy seeds you find in your morning muffin have had this coating washed off, so they pose very little risk of even slight intoxication.

Naturally derived opioids include:

Semi-synthetic opioids

Semi-synthetic opioids are half-natural, half-artificial. Scientists synthesize them in a lab from codeine or morphine, creating more potent drugs than their plant-based precursors.

The following opioids belong to the semi-synthetic category:

Synthetic opioids

Synthetic opioids are completely developed in a lab. Three examples include:

Some synthetic opioids are more powerful than their natural or semi-synthetic cousins: Fentanyl is up to 100 times stronger than morphine.

Although this extra power has benefits in a medical context, it also raises your risk of an opioid overdose if you misuse opioids or use them without guidance from a doctor. Since 2016, the majority of deaths in the opioid overdose epidemic have involved synthetic opioids.

In 2021 alone, fentanyl contributed to 88% of opioid-related deaths, amounting to a total of 71,238 fentanyl-related deaths.


Experts also classify opioids by how quickly your body metabolizes them:

  • Immediate-release medications start working right away, but their effects have a shorter duration. They tend to cause more severe withdrawal symptoms.
  • Extended-release medications take more time to work, but they also last longer.

Some opioids come in both extended-release and immediate-release forms.

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Opioids work by mimicking naturally occurring chemicals in your body called endorphins.

Endorphins help:

  • regulate your breathing
  • slow down digestion
  • encourage social bonding
  • turn on your body’s reward system during sex, eating, and exercise

Your body releases endorphins during painful and pleasurable experiences. They attach to your nerves’ opioid receptors, blocking the neurological “doorway” so other chemicals carrying pain or stress signals can’t get through. In a nutshell, your body uses endorphins to turn down its alarm system and give the all-clear signal.

Opioids also attach to these same nerve receptors, often more effectively than endorphins do. Synthetic and semi-synthetic opioids, in particular, often bond more efficiently with opioid receptors than opiates. That’s why these drugs can relieve more severe pain than your body could otherwise handle — and why they create a greater sense of euphoria than, say, a natural runner’s high.

Using opioids, especially long term or in large doses, may close off these receptors to the point of disrupting important bodily functions, like breathing and digestion.

When opioids repress these functions too much, this can cause an overdose — when your body stops working altogether.

Opioid receptors

Your body can produce multiple kinds of endorphins. It also has three types of opioid receptors. All three types play a role in pain relief, but they also have other unique functions in your body:

  • Mu opioid receptors (MORs) produce feelings of euphoria and reinforcement for rewards. They’re also responsible for side effects like physical dependence, constipation, and respiratory depression.
  • Kappa opioid receptors (KORs) produce a sedative effect. They’re also responsible for the feelings of depression or stress that often accompany long-term opioid use.
  • Delta opioid receptors (DORs) help reduce anxiety.

Heroin and prescription opioids tend to bond primarily with MORs, so using these types of opioids may increase your risk of dependence or addiction.

Prescription opioids are generally safe to take if you follow your doctor’s instructions.

Just keep in mind that they can cause side effects, like most other medications.

Short-term effects

When you use opioids, you may quickly notice side effects like:

In some cases, these side effects may escalate into a medical crisis. Signs of an opioid overdose include:

  • difficulty breathing
  • slower heart rate
  • bluish lips or fingertips
  • vomiting
  • pinpoint pupils
  • loss of consciousness

If you or someone else develop any of these symptoms after taking opioids, call 911 or local emergency services immediately. The sooner you get medical attention, the better your chances of avoiding permanent brain damage or death.

Using Narcan to treat overdose

Narcan (naloxone) is a medication approved by the Food and Drug Administration (FDA) that can reverse an opioid overdose. You can buy this medication over the counter. It comes in the form of a nasal spray.

Narcan’s effects are temporary, so you still need to get medical attention right away. After administering it, stay with the person to make sure they stay awake and keep breathing.

Long-term effects

The longer you use opioids, the greater chance you have of experiencing chronic health issues.

Long-term opioid use may contribute to physical and mental health side effects, like:

Reducing your dose or switching medications may help alleviate many of these symptoms. Keep in mind, though, that you’ll always want to get professional guidance before changing your dose or taking your medication less often. Your healthcare team can help you lower your dose safely while minimizing withdrawal symptoms.

More than 2.7 million people in the United States have OUD, also called opioid addiction. You may have this mental health condition if you’ve experienced at least two of the following symptoms within the last year:

  • You find yourself taking more opioids than you originally intended, or taking them for longer periods.
  • You’ve tried to use fewer opioids, or stop taking them altogether, but you haven’t been able to cut back.
  • You frequently experience cravings.
  • You spend a lot of time considering how to get more opioids or recovering from the side effects of taking them.
  • Opioid use has interfered with your responsibilities at school, work, or home.
  • Opioid use has started to affect your social life or personal relationships, but you keep taking them.
  • You’ve stopped hobbies or recreational activities because of your opioid use.
  • You combine opioids with alcohol or illegal drugs.
  • You keep using opioids even if they contribute to physical or mental health symptoms.
  • You need larger amounts of opioids to get the same effect as when you first started taking them.
  • Your body has developed a dependence on opioids to function. When you stop taking them, you notice aching, insomnia, and other withdrawal symptoms.

Just know all of these criteria may not necessarily apply when you take opioids under medical guidance.

For example, if prescription opioids for cancer-related pain have improved your quality of life, your desire to continue your treatment program wouldn’t be considered a sign of OUD.

Learn about OUD stigma and how to deal with it.

OUD and surgery

Healthcare professionals frequently prescribe opioids for pain after surgery. If your doctor has given you pain medication to help your recovery, you may wonder about your risk of OUD.

Relatively few people doing short-term opioid therapy after surgery develop chronic opioid use or OUD. A 2020 literature review of more than 1.9 million people taking opioids after surgery found that only 6.7% of them continued filling opioid prescriptions past 3 months. Among people who had never used opioids before, that rate dropped to 1.2%.

That said, anyone can develop OUD. If you have a personal or family history of substance use disorders, you may want to let your doctor know before your surgery.

Your medical history won’t necessarily prevent you from getting pain medication, but it can prompt your care team to offer additional safeguards to help lower your risk of OUD.

If you only use opioids for a few days after surgery, you can simply stop taking them once the severity of your pain improves, which usually happens within a few days. From there, over-the-counter pain relievers can help address milder lingering pain.

But if you’ve taken opioids for more than a few days, you’ll want to get professional support for tapering your dose, or reducing it gradually.

The importance of tapering

Tapering your dose is essential because it helps minimize your risk of withdrawal symptoms.

Withdrawal symptoms can range from mild to life threatening. Their severity typically depends on how long you’ve taken opioids and at what dose.

Taking opioids for a longer period of time, and at a higher dose, increases your chances of experiencing more severe symptoms.

The length of the tapering period typically depends on how long you’ve taken opioids.

Your doctor may recommend a slower pace if you’ve taken opioids for more than a year. Slower tapers involve decreasing your dose by about 10% each month.

If you’ve only taken opioids for a few weeks or months, your doctor may instead recommend decreasing your dose by about 10% each week.

Tapering guidelines can vary depending on your specific health needs and situation. Your care team can offer more personalized guidance on the right plan for you.

Support for OUD

Treatment for OUD often involves a combination of medication and counseling.


Medications for OUD can help reduce withdrawal symptoms, like cravings. The FDA has approved three medications for OUD:

  • Buprenorphine helps reduce cravings and withdrawal symptoms. It may blunt the euphoric effects of opioids.
  • Methadone has the same effects as buprenorphine.
  • Naltrexone blocks the euphoric and sedative effects of opioids.

Buprenorphine and methadone are both opioids themselves. But because of how they bind to opioid receptors, they offer some protection against overdose from other opioids while also minimizing withdrawal symptoms.


Therapy approaches often used to help treat OUD include cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT).

Check out our top 10 picks for online therapy.

The specific techniques your therapist uses may depend on what you want to accomplish in counseling. Common therapy goals include:

  • identifying and resisting triggers for opioid use
  • learning to emotionally adjust to, accept, and navigate chronic health issues
  • recognizing and addressing underlying mental health concerns, like trauma, anxiety, or depression

Here’s how to find the right therapist.

Opioids can provide powerful pain relief and sedation, which makes them essential for treating severe pain, such as cancer-related pain or pain after major surgery. However, they may also cause unwanted side effects, like constipation and drowsiness.

Long-term use can make it difficult to stop taking opioids without support — but you do have options for treatment, so you don’t have to manage your symptoms on your own. Seeking help sooner rather than later can make a big difference for your health and well-being.

You can start your search by using the SAMHSA Opioid Treatment Program Directory, or explore treatment programs in your area by using the Department of Health and Human Services treatment center directory.

Emily Swaim is a freelance health writer and editor who specializes in psychology. She has a BA in English from Kenyon College and an MFA in writing from California College of the Arts. In 2021, she received her Board of Editors in Life Sciences (BELS) certification. You can find more of her work on GoodTherapy, Verywell, Investopedia, Vox, and Insider. Find her on Twitter and LinkedIn.