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Find out what fentanyl is, how you have it and other important information about having fentanyl. 

What it is

Fentanyl is a type of opioid painkiller. It treats moderate to severe long term (chronic) cancer pain. It can also help to control breakthrough cancer pain. Breakthrough pain is pain that occurs despite taking regular painkillers for long term pain. 

Breakthrough pain can happen suddenly and can be very severe. It might be caused by movement or activities such as walking, changing position, or coughing. It can also be unexpected and happen for no apparent reason. Some types of fentanyl work very quickly and work very well for this type of pain.

How it works

As an opioid, fentanyl works by mimicking the body’s natural painkillers, endorphins. These control pain by blocking pain messages to the brain. 

How you have it

You can only get fentanyl on prescription from a doctor. Your dose of fentanyl will be specific to you and depends on the amount you need to control your pain. You can have fentanyl in different ways.

The brand names of fentanyl patches include Durogesic DTrans, Tilofyl and FENCINO. They are for long term cancer pain. You stick a fentanyl patch on your skin and the drug is absorbed into your body over a period of time. Doctors call this a transdermal system.

The best areas to put the patches are on the inner part of your upper arm, the top of your chest, or on your back. To make sure that you get the dose of fentanyl that you need, find an area of skin that is:

  • clean and dry
  • not too hairy - you can cut the hair but shouldn't shave the area
  • not irritated or sore
  • not a previous radiotherapy site
  • flat and not likely to wrinkle when you move
  • has no creams, soap or lotions on it

All of these can change how you absorb the drug so you may absorb more or less.

You will need to have another type of painkiller when you put the first patch on. The patches take a while to reach the correct dose at first, and won’t work fully for 24 hours. They usually last for 72 hours (3 days). When you need to change a patch, put the new one on a different area of skin. Your skin can get sore or itchy if you keep putting them in the same place. Don't forget to take off the old patch.

When you open the packet you need to be careful not to damage the patch, so don’t use scissors. When you stick the patch onto your skin, press hard for about 30 seconds with the palm of your hand. Make sure that it has stuck, especially around the edges.

The patch can loosen and might not work so well when it is hot or you are sweating a lot. If it becomes loose, you may need to stick some tape over the patch. If it becomes a problem, talk to your nurse or doctor. Tell them if you have a high temperature (fever) because this can sometimes increase the amount of fentanyl you absorb. Don’t put any direct heat on the patch, such as a hot water bottle, because this can also increase the amount you absorb.

Remember that when you remove the patch it can take 24 hours for the effects of the drug to wear off.

The brand name for this lozenge on a stick is Actiq. It gives fast pain relief. You suck the lozenge and move it around your mouth so that it is in contact with the mouth lining. You might have it to relieve any pain that you get between doses of other painkillers. This is known as breakthrough pain. 

You usually suck the lolly for about 15 minutes. It should start to control pain within 5 minutes and work fully within 30 minutes. You must not bite, chew or swallow the lozenge. 

The brand names are Abstral or Effentora. Fentanyl tablets give fast relief of pain. You might have them to relieve any pain that you get between doses of other painkillers (breakthrough pain). You put the tablet under your tongue and it dissolves. It usually starts to control pain within 5 minutes and works fully within 30 minutes.

The brand name is Breakyl. It is a small dissolvable square that you fit into the side of your cheek. The dissolvable square is called a buccal film. One side is pink and the other side is white. The pink side contains fentanyl.  It gives fast relief of pain. 

You use your tongue to wet the inside of your cheek. Or you can rinse your mouth with water. Then with dry hands you put the square into your mouth so that the pink side is in contact with the inner lining of your cheek. You need to press and hold it in place for a minimum of 5 seconds until it sticks firmly. Then the square should stay in place on its own. It usually dissolves completely within 15 to 30 minutes.

After 5 minutes you can drink liquids. But you shouldn't eat food until the square has completely dissolved. You also need to avoid moving the square with your fingers or tongue. You mustn't chew or swallow the square as then it won't work properly in controlling the pain. 

The brand names are Instanyl and PecFent. You spray the liquid up your nose and it is absorbed from the nasal lining. It gives very fast pain relief and works about 5 minutes more quickly than fentanyl lollies or tablets. It can be very helpful in giving quick pain relief to people who have nausea or vomiting, a very sore or dry mouth, or who can't swallow.

When you have it

Your doctor or nurse will give you instructions on how much to have and when to have it.


You have blood tests before and during your treatment. They check your levels of blood cells and other substances in the blood. They also check how well your liver and kidneys are working.

Side effects

Important information

Other medicines, foods and drink

Cancer drugs can interact with some other medicines and herbal products. Tell your doctor or pharmacist about any medicines you are taking. This includes vitamins, herbal supplements and over the counter remedies.

Grapefruit and grapefruit juice

You should not eat grapefruit or drink grapefruit juice when you are taking this drug because it can react with the drug.

Alcohol and fentanyl

Don't drink alcohol while using fentanyl because it can increase the drowsiness and other side effects.

Drowsiness or slow breathing

Fentanyl can slow your breathing or make you very sleepy if the dose is too high. 

If you have these effects tell your doctor or nurse straight away and call another person nearby to stay with you.

Treatment for other conditions

Always tell other doctors, nurses, pharmacists or dentists that you’re having this treatment if you need treatment for anything else, including teeth problems.

Pregnancy and contraception

This treatment might harm a baby developing in the womb. It is important not to become pregnant or father a child while you're having treatment and for a few months afterwards. Talk to your doctor or nurse about effective contraception before starting treatment.


Don’t breastfeed during this treatment because the drug may come through into your breast milk.

Driving and using machinery

Don't drive or operate machinery or tools if you have side effects such as dizziness, tiredness, sleepiness or blurred vision.

Sugars and fentanyl

Some fentanyl lozenges and tablets contain types of sugar called glucose or sucrose. If you have diabetes, you need to take this into account. The sugars can also harm your teeth. Make sure you clean your teeth regularly. 

Worries about addiction

Because fentanyl is an opioid, some people worry about becoming addicted. When you take an opioid to control pain, you are very unlikely to become addicted. The body uses the drug to control pain, not to make you feel high.

More information about this treatment

For further information about this treatment go to the electronic Medicines Compendium (eMC) website.

You can report any side effect you have to the Medicines Health and Regulatory Authority (MHRA) as part of their Yellow Card Scheme.

Information and help

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