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Side Effects

Opioids for Cancer Pain

Opioids are types of medicine used to relieve moderate to severe pain. They are also called opiates or narcotics and are a type of analgesic (painkilling) medicine. Opioids work in the brain and other parts of the body by attaching to pain receptors to block the feeling of pain. Some people with cancer need opioids for cancer-related pain.

Common opioids for cancer care

Here are some of the common opioids used in cancer care. Brand names are in parentheses.

  • Fentanyl (Actiq, Duragesic, Fentora, Lazanda, Subsys, and others)
  • Hydrocodone
  • Hydromorphone (Dilaudid)
  • Methadone (Dolophine, Methadose)
  • Morphine (Apokyn, Avinza, Kadian, MS-Contin, and others)
  • Oxycodone (OxyContin, OxyIR, Roxicodone)
  • Oxymorphone (Opana)
  • Tapentadol (Nucynta)
  • Tramadol (Ultram)

Extended release opioids

Opioids that are called extended release (ER), long-acting (LA), controlled release (CR), and sustained release (SR) are all long-acting forms. This means they release a little bit of the medicine over a longer period. They are often taken once or twice a day to treat chronic pain. A low dose of opioids might be prescribed first and then changes can be made based on how you’re feeling.

Immediate release opioids

Immediate release (IR) opioids take effect more quickly over a shorter period (short-acting forms). These opioids are used to treat acute pain and breakthrough pain. They might be taken several times a day as needed.

There are pros and cons to long-acting and short-acting opioids.

  • Long-acting opioids take longer to work, but they provide ongoing relief for a longer time.
  • Short-acting opioids work quickly, but they don’t provide relief for a long time.

At times, short-acting opioid might be used with a long-acting opioid to give steady relief.

Sometimes, the same opioid is used to treat both chronic and breakthrough pain. Morphine sulfate immediate release (MSIR) is a short-acting form of morphine. Morphine sulfate-controlled release (MS Contin) is a long-acting form of morphine. Someone might be prescribed both MSIR and MS Contin to get better pain control. It is important to know which you are taking and how you should take it.

Opioid and non-opioid drug combinations

Some opioids are combined with non-opioids in one medicine for better pain relief. Your doctor will review any combination of medicine for interactions and possible serious side effects.

See Non-opioids and Other Medicines to Treat Cancer Pain for more on acetaminophen and NSAIDs (nonsteroidal anti-inflammatory drugs) like aspirin and ibuprofen.


Oxycodone pills might also contain aspirin, acetaminophen, or ibuprofen. For instance:

  • Combunox has ibuprofen
  • Percodan has aspirin
  • Percocet, Roxicet, Roxilox, Oxycet, and Tylox all have acetaminophen


Hydrocodone may be combined with acetaminophen or ibuprofen. For instance:

  • Vicodin, Zydone, Norco, and Lortab have acetaminophen
  • Vicoprofen and Reprexain have ibuprofen

How to get pain relief with opioids

It may take a few changes to find what works best for you. Do not change how much or how often you take pain medicine without talking to your cancer care team first. If changing the dose or frequency doesn’t work, they may prescribe a different medicine or add a new one to what you’re already taking. Talk to your cancer care team if your medicines aren’t relieving your pain.

Learn more about developing a pain control plan with your cancer care team.

How to use opioids safely

Opioids can be taken safely to get pain relief. Opioids can affect each person differently and should be used carefully for people of different ages. Some opioids cannot be given to older adults, young children, or certain people being treated for other medical conditions.

Opioids should be taken as prescribed by your cancer care team and should be used very carefully for several reasons:

  • Some pain medicines may affect how other medicines work.
  • Pain medicines can affect people differently.
  • While opioids are good at managing pain, they can be misused

Your cancer care team may prescribe opioids for increasing or severe pain and will talk to you about how to safely take opioids. Talk to your cancer care team to get answers to your questions or concerns.

If you are taking opioids, here are some important tips:

  • Store your medicines in a place no one else can get to them, such as in a locked box.
  • Only take opioids that your cancer care team tells you to take. Don’t take more or less than you are prescribed.
  • Don’t share your medicine with anyone.
  • If you are seeing more than one doctor, make sure they know all the medicines you are taking. Opioids can affect how other medicines work, so it’s important for each doctor to know everything you’re taking.
  • If you drink alcohol or take tranquilizers, sleeping pills, antidepressants, antihistamines, or any other medicines that make you sleepy, tell your doctor before starting opioids.
  • Taking opioids (even small doses) while drinking alcohol or taking tranquilizers can cause serious problems. Taking opioids and these substances can lead to an overdose and symptoms like weakness, trouble breathing, confusion, and anxiety.
  • If you have leftover or expired opioid medicines, dispose of them safely. The FDA Safe Disposal site has information about how you can return your unused medicines. You might also be able to return them to your local pharmacy.

Your cancer care team might ask you questions to make sure it is safe for you to take opioids at home before prescribing them. They might ask who you live with, if anyone there has a history of addiction, if children are in the home, or how your medicines are stored.

Risk and signs of opioid overdose

Some things that can increase a person’s risk of opioid overdose include:

  • Conditions that affect breathing, like sleep apnea or chronic obstructive pulmonary disease (COPD)
  • Taking medicines for anxiety (such as Ativan, Xanax, or Valium) with opioids
  • Had an overdose in the past
  • Using illegal drugs
  • Taking medicine for opioid use disorder (such as methadone or Suboxone)
  • Being over the age of 65 and having a non-opioid substance use disorder, such as alcohol, or a mental health disorder.

Taking too many opioids can slow or even stop a person’s breathing. Other signs of opioid overdose include:

  • Small, pinpoint pupils
  • Loss of consciousness (unable to wake someone up)
  • Choking or gurgling sounds
  • Cold or clammy skin
  • Pale or bluish skin in fair-skinned people; in people with darker skin, it might turn grayish or ashen.

Naloxone (Narcan) is a nasal spray that blocks the effects of opioids to stop the effect of an overdose. Your doctor might prescribe Narcan for you to have on hand or tell you where you can get it. All 50 states allow Narcan to be sold over the counter without a prescription. Your cancer care team might suggest that you keep naloxone (Narcan) where you can quickly get to it while you are taking opioids. This is even more important if you are taking a high dose of opioids or are at a higher risk of overdose.

If you decide to use Narcan, keep it where you can get to it fast and make sure anyone you live with knows where it is and how to use it. Call your cancer care team to talk you through how to use it.

Opioid tolerance and addiction

Over time, some people might need more of their pain medicine to get relief. They may have had a lower dose that used to work but now does not. This may be because the pain has increased, or they have developed a drug tolerance (your body gets used to the amount of opioid you’re taking, and it no longer relieves pain the way it did). Many people don’t develop a tolerance to opioids. But if you do, small increases in the dose or a change in the kind of medicine might help relieve the pain.

When you no longer need opioids

You should not suddenly stop taking opioids. People who need or want to stop taking opioids are usually tapered off (weaned off) the medicine slowly so that their bodies have time to adjust. It is normal for people's bodies to become dependent on opioids, so it takes time to adjust to not having them.

If you suddenly stop taking opioids and develop a flu-like illness, excessive sweating, diarrhea, or any other unusual reaction, tell your cancer care team. These symptoms can be treated and tend to go away in a few days or weeks. Check with your doctor about the best way to taper off your pain medicines and minimize these side effects.

A person with an addiction seeks to take opioids repeatedly to feel good. The craving for opioids can be so strong that it causes problems at work, with family, and daily activities. Someone with an addiction may have withdrawal symptoms if they cannot get the opioids their brain is used to having.

Symptoms of withdrawal are:

  • Anxiety and depression
  • Chills and sweats
  • Belly cramps and diarrhea
  • Trouble sleeping and staying asleep

It’s important to know that not everyone who uses opioids will become addicted or misuse them. Opioids can be safely taken when used responsibly and as prescribed.

Side effects of opioids

It is normal to have side effects when taking opioids, but everyone might not have side effects. The most common side effects are:

  • Sleepiness
  • Constipation
  • Nausea and vomiting

Some people might also have:

  • Dizziness
  • Itching
  • Nightmares, confusion, and hallucinations
  • Slow or shallow breathing
  • Trouble urinating (‘peeing’ or emptying your bladder when going to the bathroom)

Many side effects from opioid pain medicine can be managed. Some of them such as nausea, itching, or drowsiness, might go away after a few days as your body adjusts to the medicine. If you're having any side effects, let your cancer care team know and ask for help managing them.

Drowsiness or sleepiness

You might find that you feel sleepy when you first start taking opioids.  If pain has kept you from sleeping, you may sleep more for a few days after starting opioids while you “catch up” on your sleep.

You also will get less sleepy as your body gets used to the medicine. Call your cancer care team if you still feel too sleepy for your normal activities after you’ve been taking the medicine for a week.

But if you continue to have drowsiness, or it gets worse and it becomes more of a problem, ask your cancer care team:

  • If you can take a smaller dose more often or an extended-release opioid.
  • What you can do to get better pain relief, if the opioid is not relieving the pain. The pain itself may be tiring you out. In this case, better pain relief may lead to less sleepiness.
  • For a small decrease in the opioid dose. If the drowsiness is very bad, you might be taking more medicine than you need.
  • About changing to a different medicine.
  • If you can take a mild stimulant such as caffeine during the day.

Sometimes it may be unsafe for you to drive a car, or even to walk up and down stairs alone. Don’t do anything that requires you to be alert until you know how the medicine affects you.


Opioids cause constipation in most people, but it can often be prevented or controlled. Opioids slow the movement of stool through the bowels, which allows more time for water to be absorbed by the body. This makes the stool harder.

When you start taking opioids, your doctor might suggest taking a laxative, stool softener, or other treatment to help keep your stool soft and your bowels moving. See Constipation for more information.

Nausea and vomiting

Nausea and vomiting caused by opioids usually go away after a few days of taking the medicine. See Nausea and vomiting for more information.

Some people think they’re allergic to the opioid if they have nausea after they take one or more doses. Nausea and vomiting alone don't usually mean you're having an allergic reaction.  

But if you have a rash or itching along with nausea and vomiting, you might be having an allergic reaction. If this happens, stop taking the medicine and call your doctor right away. If you have swelling in your throat, hives (itchy welts on the skin), or trouble breathing, get help right away.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

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Last Revised: March 29, 2024

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