Strong painkillers

What are opioids?

Opioids (sometimes called opiates) are medicines used to treat pain.

There are many different types of painkillers that are suitable for different types of pain. Most doctors will start off prescribing a lesser strength painkiller such as paracetamol or ibuprofen.

If these do not work, depending on the type of pain you have, your doctor may consider prescribing a strong painkiller such as an opioid.

Types of opioids

Opioid medications are usually divided up into two groups:

• Weak opioids - these include codeine and dihydrocodeine.

• Strong opioids - these include tramadol, buprenorphine, methadone, diamorphine, fentanyl, hydromorphone, morphine, oxycodone, and pethidine.

Even though the strong opioids are classified together, they can also vary a lot in strength. The stronger ones may be ten times stronger than the weakest. Strong opioids are usually prescribed for more severe types of pain - for example, immediately after an operation. They are also often used for pain in people with cancer.

The weaker opioids are usually taken as tablets. There are dispersible and liquid forms. They may come in brands which combine paracetamol and the opioid.

Strong opioids can be taken as:

• Liquid or syrup.

• Quick-acting tablets and capsules.

• Slow-release tablets and capsules.

• Sachets.

• Tablets that are held in the mouth - next to the gum (buccal tablets).

• Patches for the skin.

• Intranasally (fentanyl spray).

• Injections, which may be under the skin, into the vein or into a muscle.

They all come in various different brand names. Once you have started taking one brand it is usually best to avoid changing to a different one to avoid confusion or mistakes.

Although there are several different types of strong opioid, the most commonly prescribed is morphine.

How do opioids work?

Opioids work by attaching to opioid receptors in the brain and spinal cord, the gut and other parts of the body. This leads to a decrease in the amount of pain felt.

How are opioids taken?

Each different opioid medicine will have different instructions. The doctor and pharmacist will explain exactly when and how to take them.

Morphine

The principles of taking morphine are important and it is a good idea to understand how and why morphine is prescribed in a certain way.

To start off with, it is usual to be given a quick-acting strong opioid (morphine tablets or liquid) as well as a slow-release morphine tablet or capsule. The slow-release preparation is usually taken once or twice a day, depending on the brand. Slow-release preparations give a steady level of medicine in the body throughout the day.

However, pain may be experienced before the next dose of slow-release morphine is due; this is called 'breakthrough' pain. Quick-acting morphine is used to ease breakthrough pain. It can be taken every four hours (or even more frequently in end-of-life care), when needed.

The slow-release morphine is started at a very low dose and increased over a number of weeks until the symptoms have eased. It is important to document how much quick-acting morphine is being used each day. This information can then be used to increase the dose of the slow-release morphine to keep people pain-free.

Slow-acting morphine which is taken twice daily should ideally be taken 12 hours apart eg, at 8am and 8pm. If two doses are taken closer together, eg 10 hours apart, then the night-time gap between doses will be longer and the pain may recur.

Side-effects of opioids

As with all medicines, opioids have a number of side-effects. In general, the stronger the opioid, the more likely the side-effects are. The most common side-effects are constipation, feeling sick (nausea) and drowsiness.

• Constipation - when starting treatment with an opioid, a laxative will also usually be prescribed. Laxatives help to ease and prevent constipation by softening the poo (stools), making it easier to pass, or they stimulate the bowel to push the stools along more quickly.

• Nausea - feeling sick is a common side-effect when first starting an opioid. This usually passes after a week or so, once the body gets used to this medication. A doctor will prescribe an anti-sickness medicine (an antiemetic) if you feel sick. If the sickness lasts for more than a week this is unusual but changing to a different opioid may help.

• Drowsiness and tiredness - again, this usually passes once used to this medication Drinking alcohol as well as taking an opioid may increase drowsiness, especially at the start of treatment or when the dose is being increased. It is better to avoid alcohol if you are taking an opioid, or to drink less alcohol than usual.

• A dry mouth can also be a problem. Some people find drinking plenty of liquids or chewing gum may help with this.

If the dose is too high, these medicines can:

• Cause significant drowsiness.

• Cause confusion.

• Cause dizziness or fainting - signs of low blood pressure (hypotension).

• Cause hallucinations (seeing things that are not there).

• Affect breathing.

These side effects need to be reported to a medical professional. The dose of the opioid may need to be decreased.

If wearing a prescribed fentanyl patch, this should be removed from the skin straightaway and medical advice should be sought if these problems develop:

• Breathing problems.

• Marked drowsiness and confusion.

• Dizziness.

• Slurred speech.

Addiction and dependence are also possible problems caused by opioids. These are discussed in the section below.

The above is not a comprehensive list - just the main possible side-effects to look out for. For a full list of possible side-effects, see the leaflet that comes with the medicine.

What is an opioid addiction?

Opioids, when taken for a long time, can cause tolerance, dependence and addiction. These are all different. Not everyone who takes opioids develops these problems. Dependence and tolerance occur more commonly than addiction.

Tolerance: after taking opioids for a long time, they do not work as well as they did in the beginning. Even though the pain is the same strength, higher doses are needed to manage it. This is called tolerance.

Dependence: people gradually becoming tolerant to an opioid may become dependent on it. Dependence is not quite the same as addiction; dependence is more of a physical problem. It means that missing a dose or stopping the opioid abruptly may cause withdrawal symptoms. Dependence is treated by a planned gradual reduction in the opioid medicine - the dose is reduced gradually so that the body becomes used to each new dose and withdrawal symptoms do not occur or are very minimal.

Withdrawal symptoms: these occur with a physical dependence to opioids (as above) and then stopping them suddenly. Withdrawal symptoms include:

• Feeling anxious or agitated.

• Not sleeping (insomnia).

• Sweating.

• Muscle pains.

• Feeling sick or being sick.

• Diarrhoea.

• Tummy cramps.

• Yawning.

Addiction: this is an excessive craving for the opioids. There is uncontrollable and compulsive use of the medicine. People who are addicted still have cravings for the opioids even after they have reduced them slowly so that they are no longer dependent. Some people are more likely to develop addiction than others and seem to be particularly sensitive to the cravings. About 1 in 5 people prescribed opioids for pain are thought to become addicted to them.

What is the usual length of treatment?

In recent years, the use of opioids for non-cancer pain has become less popular. In the early 2000s new opioids were frequently prescribed for non-cancer pain and there is much evidence of significant harm as a result. In the United States, which is where most of this prescribing took place, there have been around 15,000 deaths from opioid overdoses and it is thought that at least 2 million people in the United States are addicted to prescribed opioids.

In the last few years, this evidence, along with evidence that opioids are a relatively ineffective treatment for non-cancer chronic pain, has led to a change in the way that these are prescribed.

Opioids are still an important painkiller and work well for some types of pain. In cancer pain, they can be very effective. For some of these people, concerns about dependence are less important as they may be at the end of their life and opioids can be vital for patients to have a comfortable death. For others, opioids will be the only type of painkiller which manages their pain - this is common for cancer which has spread to the bones, for example.

People who have had surgery will frequently need opioids initially to manage the pain of their operation. The dose should be reduced as quickly as can be managed whilst ensuring a return to mobility and activity.

Strong opioids for chronic pain (pain that persists and may be permanent or long-term) are no longer routinely advised. Whereas tramadol, and sometimes even morphine, were previously frequently used for chronic non-cancer pain this is now rarely advised. The risks of strong opioids are thought to outweigh the benefits. If opioid medication is being considered then a careful discussion should be had with the doctor, discussing the long-term risks.

Sometimes, a patient may feel that an opioid drug would be useful and the doctor might disagree. In this case the doctor can refuse to prescribe the drug, if they feel that it would not be helpful or that the risks would outweigh the benefits.

The National Institute for Health and Clinical Excellence (NICE) published guidance in 2021 which advised doctors never to start opioids for chronic non-cancer pain.

How to stop taking opioids

Opioids should be stopped if:

• There is no benefit or it is no longer helping.

• There are symptoms or signs of dependence.

• The condition is resolved.

• There are more harms than benefits to taking the medication.

• The individual wants to stop taking the medication.

• The prescribing doctor feels that there are better pain strategies than opioids which may have been started before the newer guidelines became available.

However, it is important not to stop taking opioids suddenly. This is because withdrawal symptoms may develop (discussed above) if stopping them suddenly. A reducing plan should be discussed with a doctor or clinical pharmacist and the dose reduced slowly. Most people find that after some time they can reduce their dose without their pain increasing.

Opioids and driving

You should not drive if are drowsy or confused because of your medication. You are more likely to feel drowsy at the start of treatment and when you have a dose increase. So it is sensible not to drive if you have just started taking an opioid, or if the dose has been increased. Once you are settled on the dose, if you do not have any side-effects which might affect your ability to drive, you may return to driving. It is your responsibility to judge whether you are fit to drive.

It's illegal to drive if you're unfit to do so because of prescribed opioid drugs. The police can stop you and make you do a 'field impairment assessment' if they think you're on drugs. This is a series of tests - eg, asking you to walk in a straight line. If they think you're unfit to drive because of taking drugs (including prescribed drugs), you'll be arrested and will have to take a blood or urine test at a police station. Anyone with opiate dependence should stop driving and inform the DVLA, who will remove their licence for at least six months.

Can I buy opioids?

Some weak opioids are available to buy over the counter at a pharmacy. This is mainly in the form of a low dose of codeine in combination with paracetamol. The dose is lower than the dose usually prescribed by doctors.

Strong opioids cannot be bought. These medicines are only available on prescription, from a pharmacy. These medicines are also referred to as 'controlled drugs'. This means that they have to be stored in a special cupboard in the pharmacy and that doctors have to write these prescriptions in a certain way.

Travelling abroad

In order to travel abroad with a strong opioid, it is important to check first with the embassy or high commission (of the country being visited) to see if they will allow these medicines into their country. If these medicines are allowed, you may then need a letter from your doctor which states the following:

• Your name, address and date of birth.

• The dates of travel in and out of the country and the country you're visiting.

• A list of the medicines you're taking, the doses and the total amounts you're taking with you.

There will be a charge for this letter as it is not part of the NHS contract.

For people who are travelling for more than three months, a licence from the Home Office is required. Your doctor needs to fill in this form and send it to the Home Office. To obtain a licence you can:

• Contact the Home Office Drugs Licensing and Compliance Unit (DCLU) by telephoning 020 7035 6330 or e-mailing DLCUCommsOfficer@homeoffice.gsi.gov.uk; or

• Go to GOV.UK Personal import/export licence application form to download a form.

Note: it can take up to two weeks for this form to be processed by the Home Office. It is best to allow plenty of time to apply for this licence.

Who cannot take opioids?

It is very rare for anyone not to be able to take some type of opioid. Some people have serious side effects or allergic reactions to some opioids. Even then a different type of opioid might be tolerated better.

In some groups of people, doctors only prescribe opioids very cautiously and at a lower dose. For example, this might apply to people who:

• Are elderly.

• Have low blood pressure (hypotension).

• Have a condition which causes breathing problems.

• Have symptoms of a large prostate gland.

• Have an underactive thyroid gland (hypothyroidism).

• Have a history of drug dependence or misuse (this will usually mean that opioids are not recommended at all).

• Have a history of a bowel problem such as ulcerative colitis or Crohn's disease.

Other considerations

There are a number of other considerations for opioids:

• Storage - if possible, they should always be stored in a locked cupboard. They should be kept out of the reach of children.

• After treatment stops - always return opioids to your pharmacy so they can be destroyed safely.

• Take only as prescribed. Never take medicine which is prescribed for somebody else. Never take more than the prescribed dose. Only take opioids as advised by your doctor.