Taking opioids for pain

  • How do opioids work?

Opioids provide pain relief by acting on areas in the spinal cord and brain to block the transmission of pain signals.  They are considered to be some of the strongest painkillers available and are used to treat pain after surgery, serious injury and cancer. Opioid drugs can help manage some, but not all, types of chronic pain.

  • How are opioids taken?

Opioid medicines come in many different forms, such as injections, tablets, capsules, liquids, and patches.

  • When should I take my opioid medicines?

For continuous long-term pain you may be given a slow-release tablet or an opioid skin ‘patch’ which gives a steady level of medicine in the blood. Your healthcare team will find the best way to manage your pain and adjust the dose to give you pain relief most of the time. They’ll also try to minimise the side effects.  Fast-acting opioid medicines and opioids that can be injected are not very useful for managing continuous pain.

  • What dose of opioid should I take?

The correct dose of any medicine is the lowest dose that produces a noticeable benefit. It is unusual to get complete relief of pain from opioids.

You should always take the correct dose of prescribed medicines. If you feel the dose isn’t enough, or if the side effects interfere with your life, you should discuss this with your healthcare team.

  • How long will it take to work?

This depends on the form that has been prescribed. For long-term pain tablets or skin patches are most commonly prescribed. Fast acting tablets may be used when you first start trying opioid treatment; these may work within an hour and last for around three to four hours. Slow release tablets or patches take longer, up to two days to begin to have any noticeable effect.

  • What are the possible side effects?

When you first start taking opioids you can get some side effects, which usually stop after a few days. These include

  • feeling dizzy
  • feeling sick (nausea)
  • being sick (vomiting)
  • feeling sleepy
  • feeling confused

Sometimes these side effects can go on for longer than a few days. Your health-care team may give you some other medicines to help, such as anti-sickness tablets.

If pain has affected your sleep, opioids may help you to recover your normal pattern, but they should not make you drowsy in the daytime.

Opioid medicines can cause some problems when you take them for long periods of time. These problems include:

  • constipation; this is a common problem when taking opioids and does not tend to go away the longer you take opioid medicines. You may need to try laxatives to treat constipation. If you experience a lot of side effects your team may suggest changing to another opioid drug
  • itching
  • weight gain
  • lack of sex drive
  • difficulty breathing at night; this is most common if you are overweight and if you snore heavily. If you have a condition called obstructive sleep apnoea it may not be safe for you to take opioids
  • What if I forget or miss a dose?

Take it as soon as you remember!
However, if it is almost time for your next dose, skip the missed dose and take your medication as normal. 
Do not take two doses together!

  • Can I drive when I’m taking opioids?

The law in the UK allows you to drive if you are taking prescribed opioid medicines in accordance with the instructions from your prescriber (including what your prescriber advises you about driving safely). You should never drive if you feel unsafe. Your ability to drive may be affected by other medicines you are taking in addition to opioids, whether you feel tired and by your pain. You are responsible for making sure you are safe on each occasion that you drive.

The law on drugs and driving in the UK changed in 2015. If your driving is impaired for any reason, including taking medicines, it is illegal to drive. It is also now illegal to drive when you are taking opioid medicines without them being prescribed, even if you are not impaired. Preparation for the new drug driving laws involved extensive scientific research to investigate what effect opioid drugs have on the ability to drive safely. We now know that if a person is taking more than 220mg of morphine a day they are likely to have a blood level of the medicine which impairs them nearly as much as someone who is over the legal limit of alcohol. All opioid medicines have the potential to impair driving and your prescriber will advise whether the dose of opioid you are taking is likely to impair you. If you are taking a high dose of opioid your prescriber will advise you that you are probably not safe to drive and will document this in your medical notes.

The doses of opioid medicine that are likely to affect your driving are quite high and are above the level that we know is safe and effective for pain treatment.

It is unsafe to drive in the first few days after starting an opioid and for a few days after dose change (up or down). Drinking alcohol reduces the amount of opioid medicine you can take and drive safely so do not drive if you have drunk alcohol and taken opioid medicines.

  • Can I take this medicine long-term?

While opioids can have a positive benefit for some people living with long-term pain they can have serious consequences when they are not providing sufficient benefit or being taken in a manner that was not intended. It is important to consider the risks and benefits of continued opioid therapy with your prescriber on a regular basis. Recent medical literature suggests that the risks to your health increase significantly when prescribing opioids at high doses for a long period of time. If you take opioid drugs for many months or years it can affect your body in a number of ways. These problems include:

  • reduced fertility
  • low sex drive
  • irregular periods
  • erectile dysfunction in men (the inability to keep an erection)
  • reduced ability to fight infection
  • increased levels of pain

If you are worried about any of these problems, please discuss this with your healthcare team. Your team will be able to tell you whether you are at risk of developing these problems.

Everyone prescribed opioid medicines in the long-term should have them reviewed by their prescriber at regular intervals. If this does not happen ask your General Practitioner.

If you want to try reducing your dose, you should discuss this with your doctor and bring the dose down slowly.

Many people find that after a few months they can reduce their opioid dose without the pain increasing. Many individuals are able to reduce gradually their opioid dose and find that their pain is no worse. As fewer side effects are experienced, quality and enjoyment of life can improve. All of this contributes to greater physical fitness.

  • Can I drink alcohol?

Alcohol and opioids both can cause sleepiness and poor concentration. You should avoid alcohol completely when you first start on opioids or when your dose has just been increased. If you are taking opioids, you should avoid alcohol if you are going to drive or use tools or machines. When you get on a steady dose of opioid, you should be able to drink modest amounts of alcohol without getting any extra unusual effects.

  • Will my body get used to opioid medicines?

Opioids can become less effective with time (this is called tolerance). This means that your body has got used to the pain-relieving effect of the medicine. You can also become dependent on opioid medicines (dependence). This means that if you stop taking the drug suddenly, or lower the dose too quickly, you can get symptoms of withdrawal. If you run out of medicine, you can experience the same symptoms that include:

  • tiredness
  • sweating
  • a runny nose
  • stomach cramps
  • diarrhoea
  • aching muscles 
  • What about addiction to opioids?

It is rare for people in pain to become addicted to opioids.

People who are addicted to opioids can:

  • feel out of control about how much medicine they take or how often they take it
  • crave the drug
  • continue to take the drug even when it has a negative effect on their physical or mental health

We do not know exactly how many people get addicted when they are taking opioids for pain relief but it is very uncommon. It is more common if you have been addicted to opioids (including heroin) or to other drugs (or alcohol) before. Addiction may be more common in people with severe depression or anxiety. This does not mean that if you have had an addiction problem before or you are very depressed and anxious you will become addicted. It only means that you are more likely to become addicted than someone who has not had these problems. Most people do not become addicted.

So, if you have had a problem with drug or alcohol addiction in the past this doesn’t mean that you cannot take opioid medicines for your pain. However, your healthcare team will need to know about your past or current drug-taking to prescribe opioids safely and to help you watch out for warning signs.

  • What if I want to stop taking an opioid?

Do not stop taking your opioid suddenly, you may experience withdrawal symptoms. Speak to your healthcare professional (doctor, nurse, pharmacist) who will be able to supervise a gradual reduction. 

  • Is there anything else my prescriber needs to know?

  • If you are allergic to any drugs or medicines
  • If you are taking any other medicines or herbal medicines
  • If you are pregnant or breast feeding, or if you are planning to become pregnant in the future
  • If you have a kidney problem
  • If you have or have had a history of excessive alcohol use, recreational drug use or addiction to prescribed or over-the-counter medication. 


Patient Leaflet

A printable patient leaflet on taking opioids for pain

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