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Fentanyl - Brand names: Durogesic, Matrifen, Fencino, Fentalis, Suplimaze, Actiq

On this page

  1. About fentanyl
  2. Key facts
  3. Who can and cannot take fentanyl
  4. How and when to take it
  5. Taking fentanyl with other painkillers
  6. Side effects
  7. How to cope with side effects
  8. Pregnancy and breastfeeding
  9. Cautions with other medicines
  10. Common questions

1. About fentanyl

Fentanyl is a strong opioid painkiller. It's used to treat severe pain, for example during or after an operation or a serious injury, or pain from cancer.

It is also used for other types of pain that you've had for a long time when weaker painkillers have stopped working.

Fentanyl is available only on prescription. It comes as:

  • patches to be put on your skin
  • lozenges and tablets that dissolve in the mouth
  • nasal spray
  • injections (usually only given in hospital)

Fentanyl patches are used for long-lasting pain. Your doctor may also prescribe other types of fentanyl if you need extra pain relief while your regular painkiller wears off.

2. Key facts

  • Fentanyl works by blocking pain signals from travelling along the nerves to the brain.
  • The most common side effects of fentanyl are constipation, and feeling sick and sleepy.
  • It is possible to become addicted to fentanyl, but this is rare if you are taking it to relieve pain and your doctor is reviewing your treatment regularly.
  • It's best not to drink alcohol when you first start taking (or using) fentanyl. You're more likely to get side effects such as feeling sleepy or drowsy.
  • Tell a doctor or nurse about your fentanyl patch if you're having any treatment or tests. Also, remind your pharmacist about your patch when you collect prescriptions or buy other medicines.

3. Who can and cannot take fentanyl

Fentanyl can be used by most adults.

Some patches can be used in children from the age of 2 years and over. However, young children and older people are more likely to get side effects.

Fentanyl patches are usually only used if you've been taking other strong opioid painkillers. Your doctor will work out how much fentanyl to give you depending on what dose of other opioids you have been taking.

Fentanyl is not suitable for some people. Tell your doctor before starting the medicines if you:

  • have ever had an allergic reaction to fentanyl or any other medicines
  • have breathing difficulties such as asthma or a lung condition
  • are addicted to alcohol or a heavy drinker
  • have a head injury or condition that causes fits or seizures
  • have irregular heartbeats (arrhythmia)
  • have adrenal gland problems
  • have kidney or liver problems
  • have an enlarged prostate
  • have low blood pressure
  • are trying to get pregnant, are pregnant or breastfeeding

4. How and when to take it

It's important to follow your doctor's instructions.

Doses vary from person to person. Your dose will depend on how bad your pain is, how you've responded to other painkillers and if you get any side effects from fentanyl.

Fentanyl tablets, lozenges, nasal spray and injections are fast-acting. They're used for pain that is expected to last for a short time.

Fentanyl patches are slow-release. This means fentanyl is gradually released through the skin into your body.

How often to take or use fentanyl

How often you take or use fentanyl depends on the type that you've been prescribed:

  • patches – apply a new patch every 3 days (remove the old one first)
  • tablets, lozenges and nasal spray – usually only when you need them

Some patches keep working after they've been removed as they "store" fentanyl under the skin. Fentanyl patches take longer to start working but last longer. They're used for when pain lasts for a long time

Sometimes your doctor may prescribe a fentanyl patch with a fast-acting painkiller. This is to manage sudden flare-ups of pain that "break through" the relief the patches give.


Do not apply more than 1 patch at a time. Using more than 1 patch could cause a fatal overdose.

Strength of fentanyl

The different types of fentanyl come in a range of strengths:

  • patches – these release 12 micrograms to 100 micrograms of fentanyl every hour
  • nasal spray – 50 micrograms to 400 micrograms
  • tablets – 100 micrograms to 800 micrograms
  • lozenges – 200 micrograms to 1,600 micrograms

Will my dose go up or down?

Before taking or using fentanyl, you will usually start on a low dose of another type of opioid, such as morphine. This will be increased slowly until your pain is well controlled.

Once your pain is under control, your doctor may swap you to fentanyl patches. This will avoid you having to take tablets or capsules each day.

If your doctor agrees that you can stop taking fentanyl, they will reduce the strength of your patch gradually. This is especially important if you've been taking it for a long time to reduce the risk of withdrawal symptoms.

Your doctor may switch you to morphine tablets or liquid or another similar painkiller so that they can reduce the dose of fentanyl even more slowly.

How to apply a fentanyl patch

  1. Read the instructions that come with your patch carefully.
  2. Remove the patch from the packet – do not use scissors to open it as you may cut the patch. Do not cut patches unless your doctor has told you to.
  3. Keep the empty packet – you will need to put your used patch in this to keep it safe. You will then need to return it to your pharmacist who will destroy it in the right way.
  4. Peel off the plastic from the back of the patch. Do not touch the sticky side of the patch.
  5. Apply the patch to clean, dry, flat, undamaged skin. Do not touch the sticky side of the patch. Choose somewhere you can reach easily such as the top of your chest or top of your arm. Try to avoid very hairy areas, or clip the hairs first before applying the patch. If you find shaving easier, shave the area a few days before you apply the patch to make sure shaving does not irritate your skin.
  6. Do not cover the patch with anything including a dressing or tape. Talk to your doctor or pharmacist if you find your patch does not stick very well.
  7. Wash your hands after touching the patch.

Do not expose your patch to strong heat or sunlight. This can increase the amount of fentanyl that gets absorbed into your skin and can increase the risk of side effects or overdose. This includes long hot baths, saunas, electric blankets, hot water bottles, heat pads and sunbathing.

You can have showers and go swimming. Check the patch is still on properly afterwards and dry the area around the patch carefully.

What to do if your patch falls off

Check your patch every day to make sure it stays stuck to you, especially around the edges.

If your patch is missing, make sure it has not stuck to another person by mistake. It's important to find it and put it back in the packet until you can return it to your pharmacist.

If a patch falls off before the usual 3 days are up, put another patch on a different part of your body and put the old patch back in the packet it came in.

Urgent advice: Call 111 and remove the patch straight away if:

  • a fentanyl patch sticks to someone it has not been prescribed for

Changing your patch

When you change your patch, try to do it at the same time of day. Think of ways to help you remember when to change it. You could:

  • write the details on your calendar
  • write the time and date on the surface of the patch itself (using a soft-tip, permanent marker pen)
  • use a phone app or smart speaker to record the time

Storing fentanyl safely

Keep all types of fentanyl in a safe place and out of reach of children or vulnerable adults.

Used patches still contain fentanyl that can be dangerous to someone else. It's important to stick the sticky sides back together after you have taken them off and keep them safe until you can take them back to your pharmacist.

What if I forget to take or apply it?

This will vary depending on which type of fentanyl you're using. Most types of fentanyl are only taken when you need them and so you are unlikely to forget.

Never take 2 doses at the same time to make up for a forgotten one.

Always remove the old patch before applying a new one. Never use more than 1 patch at a time.

If you often forget to change patches, it may help to set an alarm to remind you.

What if I take too much?

Too much fentanyl can be dangerous. However, the amount that can lead to an overdose varies from person to person.

If you've taken too much you may feel very sleepy, sick or dizzy. You may also find it difficult to breathe. In serious cases you can become unconscious and may need emergency treatment in hospital.

Make sure the patch does not get stuck to someone else's skin, especially a child, by accident – for example if it falls off in bed or if the patch falls on the floor.

Immediate action required: Call 999 if:

  • you've taken too much fentanyl and find it difficult to breathe
  • you or someone else swallows a fentanyl patch

5. Taking fentanyl with other painkillers

It's safe to take fentanyl with paracetamol, ibuprofen or aspirin.

Do not take any painkillers with codeine including co-codamol, ibuprofen and codeine (Nurofen Plus) and Solpadeine when using fentanyl – you will be more likely to get side effects.

6. Side effects

Like all medicines, fentanyl can cause side effects in some people but many people have no side effects or only minor ones.

You are more likely to get side effects with higher doses of fentanyl.

Common side effects

Common side effects happen in more than 1 in 100 people.

Talk to your doctor or pharmacist if the side effects bother you or do not go away:

  • constipation
  • feeling or being sick (nausea or vomiting)
  • stomach pain
  • feeling sleepy or tired
  • feeling dizzy or a sensation of spinning (vertigo)
  • confusion
  • headaches
  • itching or skin rashes

Serious side effects

Serious side effects happen in less than 1 in 100 people.

Call your doctor (if you are wearing a patch, remove your patch) if:

  • your muscles feel stiff for no obvious reason
  • you feel dizzy, tired and have low energy – all of these together could be a sign of low blood pressure

Immediate action required: Call 999 if:

  • you have difficulty breathing or short shallow breathing
  • you have had a fit or seizure

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to fentanyl.

Immediate action required: Call 999 or go to A&E if:

  • you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
  • you're wheezing
  • you get tightness in the chest or throat
  • you have trouble breathing or talking
  • your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital

These are not all the side effects of fentanyl. For the full list, see the leaflet inside you medicines packet.


You can report any suspected side effect to the UK safety scheme.

7. How to cope with side effects

What to do about:

  • constipation – try to eat more high-fibre foods such as fresh fruit and vegetables and cereals. Try to drink several glasses of water or squash each day. If you can, it may also help to do some gentle exercise. Speak to your doctor about medicine to help prevent or treat constipation caused by fentanyl if your symptoms do not go away. Watch a short video on how to treat constipation.
  • feeling or being sick – this side effect should normally wear off after a few days. Stick to simple meals and do not eat rich or spicy food. Drink plenty of fluids, such as water or squash, to avoid dehydration. If you're being sick, take small, regular sips of water. Ask your doctor about anti-sickness medicine if it gets worse or lasts longer than a few days.
  • stomach pain – try to rest and relax. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help. If you are in a lot of pain, speak to your pharmacist or doctor.
  • feeling sleepy or tired – these side effects should wear off within a week or two as your body gets used to fentanyl. Talk to your doctor if they carry on for longer. Do not drink alcohol as it will make these side effects worse.
  • feeling dizzy or a sensation of spinning (vertigo) – stop what you're doing and sit or lie down until you feel better. Do not drink alcohol as it will make these side effects worse. If the feeling does not go away, do not take any more medicine and speak to a pharmacist or your doctor. Do not drive, ride a bike or use tools or machinery.
  • confusion – talk to your doctor if you feel confused, your dose may need to be changed.
  • headaches – make sure you rest and drink plenty of fluids. Do not drink alcohol while taking fentanyl as this can make headaches worse. Ask your pharmacist to recommend a painkiller. Headaches should usually go away after the first week of taking fentanyl. Talk to your doctor if they last longer than a week or are severe.
  • itching or rashes – it may help to take an antihistamine, which you can buy from a pharmacy. Check with the pharmacist to see what type is suitable for you. If symptoms do not go away or it gets worse talk to your doctor as you may need to try a different painkiller.

8. Pregnancy and breastfeeding

Fentanyl and pregnancy

Fentanyl is generally not recommended during pregnancy.

In early pregnancy, it's been linked to some problems for your baby. If you take fentanyl at the end of pregnancy there's a risk that your baby may get withdrawal symptoms or be born addicted to fentanyl.

However, it's important to treat pain in pregnancy. For some pregnant women with severe pain, fentanyl might be the best option. Your doctor is the best person to help you decide what's right for you and your baby.

For more information about how fentanyl can affect you and your baby during pregnancy, read this leaflet about fentanyl on the Bumps website.

Fentanyl and breastfeeding

Fentanyl is not usually recommended if you're breastfeeding.

Small amounts of fentanyl pass into breast milk and can cause breathing problems for your baby. Speak to your doctor as they may want to recommend a different painkiller.

Non-urgent advice: Tell your doctor if you're:

  • trying to get pregnant
  • pregnant
  • breastfeeding

9. Cautions with other medicines

Some medicines and fentanyl interfere with each other and increase the chance that you will have side effects.

Tell your doctor if you are taking any medicines:

  • to help you sleep
  • for high blood pressure
  • to help stop you feeling or being sick
  • to treat symptoms of an allergy
  • for mental health problems including depression, or to reduce stress or anxiety
  • for any infection (including HIV)
  • to control fits or seizures

Mixing fentanyl with herbal remedies and supplements

It's not possible to say that herbal medicines or remedies are safe to take with fentanyl.

They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.


Tell your doctor or pharmacist if you're taking any other medicines, including herbal remedies, vitamins or supplements.

10. Common questions

How does fentanyl work?

Fentanyl is from a group of medicines called opioids or narcotics.

It works in the central nervous system and the brain to block pain signals to the rest of the body. It also reduces the anxiety and stress caused by pain.

How long does it take to work?

This depends on the type of fentanyl you take.

A fentanyl injection into a vein gives the quickest pain relief. It works almost straight away and is usually only given in hospital.

Fast-acting fentanyl tablets, lozenges and nasal sprays take around 15 to 30 minutes to work but they wear off after 4 to 6 hours.

Fentanyl patches can take up to a day or two to start working but they will last longer. Patches are usually given after fentanyl tablets. This is to make sure that you have pain relief from the tablets until the patches start to work.

How long will I use it for?

Depending on why you're taking fentanyl, you may only need to take it for a short time.

For example, if you're in pain after an injury or operation, you may only need to take fentanyl for a few days or weeks.

You may need to take it for longer if you have a long-term condition.

Can I take it for a long time?

For some people with conditions that need long-term pain relief it may be necessary to take fentanyl for a long time.

If you need to take it for a long time your body can become tolerant to it. That means you need higher doses to control your pain.

It is possible to become addicted to fentanyl, but this is rare especially if your doctor is reviewing your treatment regularly. The dose will be reviewed to make sure you are only taking the amount you need to control your pain.

Can I become addicted to fentanyl?

Yes, fentanyl is addictive. If you need to take it for a long time, your body can become tolerant to it. That means you need higher doses to control your pain.

However, if you're using fentanyl to relieve pain (rather than using it as a recreational drug) it's very unlikely you will get addicted to it because you're not using it to get a "high".

You're more likely to get addicted if you use fentanyl when you're not in pain. It is also more likely if you've been addicted to alcohol or drugs in the past, or you have severe depression or anxiety.

This does not mean you cannot use fentanyl. However, your doctor will need to know about your past and current drug and alcohol use to be able to prescribe fentanyl safely. They will help you watch out for any warning signs of addiction.

How will I know if I'm addicted?

If you're addicted to fentanyl you may find it difficult to stop using it or feel you want to use it more often than you need to.

Talk to your doctor about getting help with addiction if you're worried or you want to stop taking fentanyl.

What will happen if I stop taking it?

If you need to take fentanyl for a long time your body can become tolerant to it.

This is not usually a problem. However, you could get withdrawal symptoms if you stop taking it suddenly.

If you want to stop taking fentanyl, talk to your doctor first. Your dose can be reduced gradually so you do not get withdrawal symptoms.

If you stop taking fentanyl suddenly it can make you:

  • feel agitated
  • feel anxious
  • shaky
  • sweat a lot


If you have been taking fentanyl for more than a few weeks, do not stop taking it without speaking to your doctor first.

What do I do with used fentanyl patches?

Fold your used patches in half so that the sticky sides stick to each other and then put it back in the packet it came in.

Return any used or unused patches to your pharmacist who will destroy them safely.

Patches can accidentally stick to another person.

Urgent advice: Call 111 and remove the patch straight away if:

  • a fentanyl patch sticks to someone it has not been prescribed for
How is fentanyl different to other opioids?

Fentanyl acts on different pain signals in the brain to some other opioids.

The pain relief and side effects will be different for everyone. Your doctor may prescribe fentanyl if you have had side effects from other opioids.

The way you take fentanyl is different to some other painkillers. Fentanyl is not absorbed very well by swallowing tablets. Instead your body absorbs it through your skin, your nostrils, or your tongue or the inside of your cheek.

Some people find skin patches more convenient as it means they do not need to take tablets or capsules regularly.

Can I drink alcohol with it?

It's best not to drink alcohol when you first start taking or using fentanyl until you see how it affects you.

Drinking alcohol while taking fentanyl will make you more sleepy and increases the risk of serious side effects.

Is there any food or drink I need to avoid?

Grapefruit juice can increase the amount of fentanyl in your body so it's a good idea not to drink more than a large glass of it.

It's best not to drink alcohol when you first start taking or using fentanyl until you see how it affects you.

Fentanyl is not generally affected by food so you can eat normally.

Will it affect my contraception?

Fentanyl does not affect any type of contraception including the combined pill or emergency contraception.

But if fentanyl makes you sick (vomit) your contraceptive pills may not protect you from pregnancy.

If this happens, follow the instructions in the leaflet that comes with your contraceptive pills.

Find out what to do if you're on the pill and you're sick or have diarrhoea

Will it affect my fertility?

There's no clear evidence to suggest that fentanyl reduces fertility in women or men.

Speak to a pharmacist or your doctor if you're trying for a baby. They may want to review your treatment.

Can I drive or ride a bike?

Do not drive a car or ride a bike if fentanyl makes you sleepy, gives you blurred vision or makes you feel dizzy, clumsy or unable to concentrate or make decisions.

This may be more likely when you first start on fentanyl but could happen at any time – for example when starting another medicine.

It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive. If you're in any doubt, do not drive.

Even if your ability to drive is not affected, the police have the right to request a saliva sample to check how much fentanyl is in your body.

GOV.UK has more information on the law on drugs and driving.

Talk to your doctor or pharmacist if you're unsure whether it's safe for you to drive while taking fentanyl.

Will recreational drugs affect it?

If you take recreational drugs, such as cannabis, cocaine and heroin, while you're taking fentanyl, you're more likely to get the serious side effects. These include breathing difficulties, heart problems such as high blood pressure, seizure or fits and even going into a coma.

Some recreational drugs, such as cannabis, will also increase the risk of side effects from fentanyl – it may make you feel really sleepy or dizzy.

Taking heroin while you're on fentanyl is especially dangerous. You're more likely to get all the side effects of fentanyl.

Tell your doctor if you think you may take recreational drugs while you're on fentanyl.

Related conditions

Page last reviewed: 15 April 2020
Next review due: 15 April 2023