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Generic name: fentanyl (sublingual) (FEN tan il sub LIN gwal)
Brand name: Abstral, Fentora, Subsys
Drug class: Narcotic analgesics

Medically reviewed by Philip Thornton, DipPharm. Last updated on Nov 5, 2019.

What is Abstral?

Abstral (fentanyl) is an opioid pain medication. An opioid is sometimes called a narcotic.

Abstral sublingual tablets are used to treat "breakthrough" cancer pain that is not controlled by other medicines.

The sublingual tablet is placed on the floor of the mouth under your tongue (sublingual) and allowed to dissolve.

Abstral is not for treating pain that is not cancer-related.


Fentanyl can slow or stop your breathing, and may be habit-forming. Use only your prescribed dose. Never share Abstral with another person.

MISUSE OF NARCOTIC PAIN MEDICINE CAN CAUSE ADDICTION, OVERDOSE, OR DEATH, especially in a child or other person using the medicine without a prescription.

Fatal side effects can occur if you use this medicine with alcohol, or with other drugs that cause drowsiness or slow your breathing.

Before taking this medicine

Do not use Abstral unless you are already using an around-the-clock opioid medicine and are tolerant to it. You should not use Abstral if you are allergic to fentanyl, or if you have:

  • severe asthma or other breathing problems; or

  • a stomach or bowel obstruction (including paralytic ileus).

To make sure Abstral is safe for you, tell your doctor if you have ever had:

  • breathing problems, sleep apnea;

  • any type of breathing problem or lung disease;

  • a head injury, brain tumor, or seizures;

  • low blood pressure, slow heartbeats or other heart rhythm disorder;

  • drug or alcohol addiction, depression, schizophrenia, or hallucinations;

  • liver or kidney disease;

  • urination problems; or

  • problems with your thyroid, gallbladder, or pancreas.

Tell your doctor if there are children living in the home where you will store this medicine. The amount of fentanyl in this medicine can be fatal to a child.

If you use Abstral while you are pregnant, your baby could become dependent on the drug. This can cause life-threatening withdrawal symptoms in the baby after it is born. Babies born dependent on habit-forming medicine may need medical treatment for several weeks. Tell your doctor if you are pregnant or plan to become pregnant.

Do not breast-feed while you are using this medicine.

How should I use Abstral?

Abstral dissolves under your tongue and will be absorbed by your body to help provide relief for your breakthrough cancer pain.

Follow all directions on your prescription label. Fentanyl can slow or stop your breathing. Never use this medicine in larger amounts, or for longer than prescribed. Tell your doctor if the medicine seems to stop working as well in relieving your pain.

Fentanyl may be habit-forming, even at regular doses. Never share this medicine with another person, especially someone with a history of drug abuse or addiction. MISUSE OF NARCOTIC MEDICINE CAN CAUSE ADDICTION, OVERDOSE, OR DEATH, especially in a person using the medicine without a prescription. Selling or giving away Abstral is against the law.

Read all patient information, medication guides, and instruction sheets provided to you. Ask your doctor or pharmacist if you have any questions.

If you have been using another form of fentanyl (injection, skin patch, "lollipop" device), your buccal or sublingual dose may be different.

Abstral comes in a blister card with four blister units. Each blister unit contains an Abstral tablet. It is important that the tablet stays sealed in the blister unit until you are ready to use it.

When you get an episode of breakthrough pain, take the dose prescribed by your healthcare provider as follows:

  • If your mouth is dry, take a sip of water to moisten it. Spit out or swallow the water. Dry your hands if they are wet before you handle Abstral tablets.

  • When you are ready to take a tablet, pull apart one of the blister units from the blister card by tearing along the dotted lines (perforations) until it is fully separated.

  • When the blister unit is fully separated, peel back the foil starting at the unsealed area where indicated. Gently remove the tablet. Do not try to push Abstral tablets through the foil. This will damage the tablet.

  • As soon as you remove the Abstral tablet from the blister unit, place it on the floor of your mouth, under your tongue, as far back as you can. Do not suck, chew or swallow the tablet. Let the tablet dissolve completely. Do not drink or eat anything until the tablet has completely dissolved under your tongue and you can no longer feel it in your mouth.

  • If more than one tablet is required, spread them around the floor of your mouth under your tongue.

You must not use more than two doses of Abstral for each episode of breakthrough cancer pain.

Take one dose for an episode of breakthrough cancer pain. If your breakthrough pain does not get better within 30 minutes after taking the first dose of Abstral, you can take one more dose as instructed by your healthcare provider.

If your breakthrough pain does not get better after the second dose of Abstral, call your healthcare provider for instructions. Do not take another dose at this time.

Wait at least 2 hours before treating a new episode of breakthrough cancer pain with Abstral.

If you only need to take one dose of Abstral for an episode of breakthrough pain, you must wait 2 hours from the time of that dose to take a dose for new episode of breakthrough pain.

If you need to take two doses for an episode of breakthrough pain, you must wait 2 hours after the second dose to take a dose for a new episode of breakthrough pain.

It is important for you to keep taking your around-the-clock opioid pain medicine while taking Abstral.

Talk to your healthcare provider if you have more than four episodes of breakthrough cancer pain per day. The dose of your around- the-clock opioid pain medicine may need to be adjusted.

Talk to your healthcare provider if your dose of Abstral does not relieve your breakthrough cancer pain. Your healthcare provider will decide if your dose needs to be changed.

Do not stop using Abstral suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to safely stop using this medicine.

Never crush or break a Abstral tablet to inhale the powder or mix it into a liquid to inject the drug into your vein.

Store at room temperature away from moisture and heat. Do not freeze. Keep track of the amount of medicine used from each new bottle. Keep your medicine in a place where others cannot get to it. Fentanyl is a drug of abuse and you should be aware if anyone is using your medicine improperly or without a prescription.

Keep this medicine out of the reach of children or pets. The amount of fentanyl in each sublingual tablet can be fatal to a child or pet who accidentally sucks on or swallows it. Seek emergency medical attention if this happens.

Carefully follow disposal instructions when this medicine is no longer needed. Do not keep leftover opioid medication. Just one dose can cause death in someone using this medicine accidentally or improperly. Ask your pharmacist where to locate a drug take-back disposal program. If there is no take-back program, throw away any unused Abstral tablets by removing them from the blister pack and flushing them down a toilet.

What happens if I miss a dose?

Since Abstral is used for pain, you are not likely to miss a dose. Skip any missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. A fentanyl overdose can be fatal, especially in a child or other person using the medicine without a prescription. Overdose symptoms may include extreme weakness or drowsiness, weak pulse, cold and clammy skin, pinpoint pupils, and slow breathing (breathing may stop).

What should I avoid while using Abstral?

This medicine may impair your thinking or reactions. Avoid driving or operating machinery until you know how Abstral will affect you. Dizziness or severe drowsiness can cause falls or other accidents.

Do not drink alcohol. Dangerous side effects or death could occur.

Grapefruit and grapefruit juice may interact with fentanyl and lead to unwanted side effects. Avoid the use of grapefruit products while taking Abstral.

Abstral side effects

Get emergency medical help if you have signs of an allergic reaction to Abstral: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Like other narcotic medicines, fentanyl can slow your breathing. Death may occur if breathing becomes too weak. A person caring for you should seek emergency medical attention if you have slow breathing with long pauses, blue colored lips, or if you are hard to wake up.

Call your doctor at once if you have:

  • slow heart rate, sighing, shallow breathing, breathing that stops during sleep;

  • severe drowsiness, feeling like you might pass out;

  • confusion, extreme fear, unusual thoughts or behavior; or

  • low cortisol levels - nausea, vomiting, loss of appetite, dizziness, worsening tiredness or weakness.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Serious side effects may be more likely in older adults and those who are malnourished or debilitated.

Long-term use of opioid medication may affect fertility (ability to have children) in men or women. It is not known whether opioid effects on fertility are permanent.

Common Abstral side effects may include:

  • headache, dizziness, drowsiness, pale skin, feeling weak or tired;

  • constipation, nausea, vomiting; or

  • swelling in your hands or feet.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Abstral?

Some drugs can raise or lower your blood levels of fentanyl, which may cause side effects or make Abstral less effective. Tell your doctor if you also use certain antibiotics, antifungal medications, heart or blood pressure medications, or medicines to treat HIV or AIDS.

Fentanyl can interact with many other drugs and cause dangerous side effects or death. Be sure your doctor knows if you also use:

  • cold or allergy medicines, bronchodilator asthma/COPD medication, or a diuretic ("water pill");

  • medicines for motion sickness, irritable bowel syndrome, or overactive bladder;

  • other narcotic medications - opioid pain medicine or prescription cough medicine;

  • a sedative like Valium - diazepam, alprazolam, lorazepam, Xanax, Klonopin, Versed, and others;

  • drugs that make you sleepy or slow your breathing - a sleeping pill, muscle relaxer, medicine to treat mood disorders or mental illness; or

  • drugs that affect serotonin levels in your body - a stimulant, or medicine for depression, Parkinson's disease, migraine headaches, serious infections, or nausea and vomiting.

This list is not complete. Other drugs may interact with fentanyl, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Frequently asked questions

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Abstral only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.