Abstral tablets (Fentanyl)

How does it work?

Abstral sublingual tablets contain the active ingredient fentanyl, which is a type of medicine called an opioid analgesic. The opioids are a group of very strong painkillers that are related to morphine.

Opioid painkillers work by mimicking the action of naturally occurring pain-reducing chemicals called endorphins. Endorphins are found in the brain and spinal cord and reduce pain by combining with opioid receptors.

Fentanyl mimics the action of natural endorphins by combining with the opioid receptors in the brain and spinal cord. This blocks the transmission of pain signals sent by the nerves to the brain. Therefore, even though the cause of the pain may remain, less pain is actually felt.

People with long-term, ongoing, severe pain, such as the pain caused by cancer, are given opioid medicines as painkillers. However, occasionally the pain can become worse despite taking these strong painkillers. This is known as 'breakthrough' pain. Abstral sublingual tablets are used to relieve this 'breakthrough' pain in people already receiving opioid painkillers.

Abstral sublingual tablets should be allowed to dissolve underneath the tongue. This allows the fentanyl to be rapidly absorbed into the bloodstream through the rich supply of blood vessels found in this area, and provide rapid relief from pain. The tablets should not be chewed, sucked or swallowed, as this would make them less effective.

What is it used for?

  • Relief of breakthrough pain in people taking regular opioid painkillers for long-term, ongoing, severe pain due to cancer.

How do I take it?

  • One Abstral sublingual tablet should be allowed to dissolve underneath the tongue. The tablet should not be chewed, sucked or swallowed.
  • If you have a dry mouth, have a drink of water before placing the tablet under your tongue.
  • You should not eat or drink anything until the tablet has completely dissolved.


  • This medicine may cause drowsiness and dizziness. If affected do not drive or operate machinery.
  • You should avoid drinking alcohol while taking this medicine as it is likely to increase the chance of you feeling drowsy or dizzy.
  • This medicine has severe side effects in an overdose. Do not exceed the dose prescribed by your doctor. If you become very sleepy or have slow and/or shallow breathing after taking this medicine, you or your carer should contact your doctor immediately and call for emergency help.
  • You should not use Abstral more than four times in one day. If your previous dose of Abstral is not relieving pain as well, or if you have more than four episodes of breakthrough pain in a day, you should tell your doctor as your pain management may need to be reviewed. You should not change your doses of Abstral or your other pain medicines on your own. This needs to be done by your doctor so that your pain and any side effects of the medicines can be monitored.
  • You should not use Abstral tablets in combination with any other fentanyl medicine prescribed for breakthrough pain.
  • If this medicine is used for prolonged periods of time, the body can become tolerant to it and it may become less effective at relieving pain. This means that with time, higher doses may be needed to control pain. With prolonged use the body may also become dependent on opioids. As a result, withdrawal symptoms can occur if all opioid painkillers are stopped suddenly. If you no longer need to use Abstral tablets but are still taking other opioids, the Abstral tablets can be stopped suddenly. However, if all opioids are to be stopped, it may be necessary to reduce treatment gradually to avoid withdrawal symptoms.
  • Abstral tablets contain a dose of medicine that can be fatal to children. Keep your tablets well out of sight and reach of children.
  • Fentanyl is a controlled drug. If you are planning to travel abroad with it you should check its legal status in the countries you are travelling through and to. There are legal limits on how much of this medicine you can take abroad with you. If you need to take more than this limit you will have to apply to the Home Office for a licence before you travel. Even if you don't need a licence, if you are taking this medicine abroad it is always a good idea to carry a letter from your doctor that confirms your need for the medicine. You should always carry the medicine in correctly labelled packaging, as dispensed by the pharmacy.

Use with caution in

  • People with inflammation or open wounds inside the mouth.
  • Elderly people.
  • Weak or debilitated people.
  • Decreased kidney function.
  • Decreased liver function.
  • Asthma.
  • Chronic obstructive pulmonary disease (COPD).
  • Myasthenia gravis.
  • People with a head injury.
  • People with raised pressure in the brain (intracranial pressure).
  • People with decreased consciousness.
  • People with a brain tumour.
  • Slow abnormal heart rhythms (bradycardia).
  • Low blood pressure (hypotension).
  • People with low levels of fluid in the body.
  • People with a history of drug dependence.
  • Men with an enlarged prostate gland.

Not to be used in

  • People who are NOT already taking opioid painkillers.
  • People with very slow, shallow breathing (severe respiratory depression).
  • Severe obstructive lung conditions such as severe chronic obstructive pulmonary disease (COPD).
  • People who have taken a monoamine-oxidase inhibitor antidepressant (MAOI) in the last 14 days.
  • The safety and efficacy of this medicine have not been established in children and adolescents under 18 years old. It is not recommended for this age group.

This medicine should not be used if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • The safety of this medicine for use during pregnancy has not been established. If used for long periods during pregnancy it may cause breathing problems and withdrawal symptoms in the baby at birth. It is not recommended for use in pregnancy, particularly during the third trimester and during labour, unless considered essential by your doctor. Seek medical advice from your doctor.
  • This medicine passes into breast milk and carries a risk of the medicine causing drowsiness and breathing problems in a nursing infant. The manufacturer states that this medicine should only be used during breastfeeding if the benefits to both mother and infant outweigh any risks of the medicine to the nursing infant. If your doctor says you can breastfeed while using this medicine, the infant should be monitored for signs of drowsiness and breathing problems. Seek further medical advice from your doctor.

Label warnings

  • This medication may cause drowsiness. If affected do not drive or operate machinery. Avoid alcoholic drink.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

Very common (affect more than 1 in 10 people)

  • Dizziness.
  • Sleepiness.
  • Headache.
  • Fatigue.
  • Nausea.
  • Sweating.

Common (affect between 1 in 10 and 1 in 100 people)

  • Dry mouth.
  • Disturbances of the gut, such as abdominal pain, indigestion, constipation, diarrhoea, vomiting.
  • Skin reactions such as rash and itching.
  • Pins and needles or numb sensations.
  • Blurred or double vision.
  • Slow, shallow breathing.
  • Inflammation of the lining of the nose (rhinitis).
  • Inflammation of the throat (pharyngitis).
  • Flushing.
  • Weakness or loss of strength (asthenia).
  • Mouth ulcers or soreness, irritation under the tongue.
  • Taste disturbance.
  • Difficulty swallowing.
  • Loss of appetite.
  • Depression.
  • Feeling of well-being, optimism and cheerfulness (euphoria).
  • Abnormal thinking.
  • Impaired concentration.
  • Confusion.
  • Anxiety.
  • Hallucinations.
  • Twitching.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

  • A general feeling of being unwell (malaise).
  • Mood swings.
  • Spinning sensation.
  • Decreased heart rate (bradycardia).
  • Difficulty passing urine (urinary retention).

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while using this one, to ensure that the combination is safe.

This medicine should not be taken by people who are taking a monoamine oxidase inhibitor antidepressant (MAOI), for example the antidepressants phenelzine, tranylcypromine or isocarboxacid, or by people who have taken one of these medicines in the last 14 days.

There may be an increased risk of side effects such as drowsiness, sedation, low blood pressure and slow, shallow breathing, if this medicine is used with other medicines that have a sedative effect on the central nervous system. These include the following:

  • antipsychotics, eg haloperidol
  • barbiturates, eg phenobarbital, amobarbital
  • benzodiazepines, eg diazepam, temazepam
  • general anaesthetics
  • muscle relaxants
  • other opioid painkillers, eg morphine, codeine
  • sedating antihistamines, eg chlorphenamine, hydroxyzine
  • sleeping tablets, eg zopiclone
  • tricyclic antidepressants, eg amitriptyline.

The following medicines can decrease the breakdown of fentanyl by the liver and so could increase the risk of fentanyl side effects:

  • azole antifungals such as ketoconazole, itraconazole or fluconazole
  • cimetidine
  • macrolide antibiotics such as clarithromycin, erythromycin or telithromycin
  • protease inhibitors, eg ritonavir.

You should let your doctor know if you experience any signs of increased fentanyl side effects if you are prescribed one of these medicines, for example, trouble breathing or shallow breathing, tiredness, difficulty thinking, walking or talking normally, or feeling faint, dizzy or confused. Your doctor may need to decrease your dose of fentanyl.

The following medicines may increase the breakdown of fentanyl by the liver and as a result your doctor may need to increase your fentanyl dose if you are prescribed one of these:

  • phenytoin
  • rifampicin.

Other medicines containing the same active ingredient

Actiq lozenges Durogesic Dtrans patches Effentora tablets
Fentalis patchesInstanyl nasal spray Matrifen patches
Mezolar patchesOsmanil patchesPecFent nasal spray
Tilofyl patchesSublimaze injectionVictanyl patches

Fentanyl patches and injection are also available without a brand name, ie as the generic medicine.