Fentanyl citrate (By mouth)


Fentanyl Citrate (FEN-ta-nil SIT-rate)

Treats cancer pain in patients whose pain is not always relieved by other pain medicines. This medicine is a narcotic pain reliever.

Brand Name(s)


When This Medicine Should Not Be Used

How to Use This Medicine


  • Your doctor will tell you how much of this medicine to use and how often. Your dose may need to be changed several times in order to find out what works best for you. Do not use more medicine or use it more often than your doctor tells you to.
  • Do not chew, suck, or swallow the sublingual tablet. Place the tablet under the tongue until it is dissolved. Do not eat or drink anything until the tablet is completely dissolved. If you take 2 or more tablets at a time, place all of the tablets under the tongue together.
  • Use only the brand of this medicine that your doctor prescribed. Different brands may not work the same way. Abstral® sublingual tablet works differently than other fentanyl products, even at the same dose (number of milligrams). Do not substitute or convert it to other products containing fentanyl.
  • This medicine is available only under a registered distribution program called REMS (Risk Evaluation and Mitigation Strategy) Program. You will be asked to sign an agreement form before you take this medicine. This form tells you about the benefits and risks of using this medicine. Make sure you understand what is on the form before you sign it.
  • This medicine should come with a Medication Guide. Read and follow these instructions carefully. Ask your doctor or pharmacist if you have any questions. Ask your pharmacist for the Medication Guide if you do not have one.

If a dose is missed:

  • If you miss a dose or forget to use your medicine, use it as soon as you can. If it is almost time for your next dose, wait until then to use the medicine and skip the missed dose. Do not use extra medicine to make up for a missed dose.

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed. To dispose any unneeded tablets: remove the tablet from its blister cards and flush down the toilet. Do not flush the blister cards or cartons down the toilet.
  • Keep all medicine away from children and never share your medicine with anyone.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you are also using clarithromycin (Biaxin®), itraconazole (Sporanox®), ketoconazole (Nizoral®), or nefazodone (Serzone®). Tell your doctor if you are also using aprepitant (Emend®), cimetidine (Tagamet®), diltiazem (Cardizem®, Dilacor XR®), erythromycin (Ery-Tab®), fluconazole (Diflucan®), telithromycin (Ketek®), or verapamil (Calan®, Isoptin®, Verelan®). Make sure your doctor knows if you have used an MAO inhibitor (MAOI), such as Eldepryl®, Marplan®, Nardil®, or Parnate® within the past 14 days.
  • Make sure your doctor knows if you are also using St. John's wort, modafinil (Provigil®), pioglitazone (Actos®), rifabutin (Mycobutin®), rifampin (Rifadin®, Rimactane®), troglitazone (Rezulin®), a steroid medicine (such as dexamethasone, prednisolone, prednisone, or Medrol®), medicine for HIV or AIDS (such as efavirenz, indinavir, nelfinavir, nevirapine, ritonavir, saquinavir, Crixivan®, Fortovase®, Invirase®, Norvir®, Sustiva®, Viracept®, or Viramune®), or medicine for seizures (such as carbamazepine, oxcarbazepine, phenobarbital, phenytoin, Dilantin®, Tegretol®, or Trileptal®).
  • Tell your doctor if you are using any medicines that make you sleepy. These include sleeping pills, cold and allergy medicine, narcotic pain relievers, and sedatives.
  • Do not drink alcohol while you are using this medicine.
  • Do not eat grapefruit or drink grapefruit juice while you are using this medicine.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, lung disease or breathing problems such as asthma or chronic obstructive pulmonary disease (COPD), low blood pressure, heart rhythm problems (such as slow heart rate), seizures (convulsions), depression, or mental problems. Also tell your doctor if you have had a recent head injury or other problems that could increase the pressure in your head. Tell your doctor if you also have a history of drug or alcohol abuse or addiction.
  • This medicine may cause problems with breathing, which can be serious and life-threatening. This is more likely in patients with lung disorders, the elderly, very weak patients, or those who use large doses of this medicine. Call your doctor right away if you have shortness of breath, or irregular, fast, slow, or shallow breathing after taking this medicine.
  • This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert. You may also feel lightheaded when standing up suddenly from a sitting or lying position, so get up slowly.
  • This medicine can cause serious illness or even death if taken by a child or by anyone who is not already taking prescription medicine on a regular schedule for cancer pain.
  • Do not stop using this medicine suddenly without asking your doctor. You may need to slowly decrease your dose before stopping it completely.
  • This medicine may be habit-forming. If you feel that the medicine is not working as well, do not use more than your prescribed dose. Call your doctor for instructions.
  • This medicine may cause constipation. This is more common if you use it for a long time. Ask your doctor if you should also use a laxative to prevent and treat constipation.
  • If your symptoms do not improve or if they get worse, call your doctor.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Fast, slow, or uneven heartbeat.
  • Lightheadedness, dizziness, severe drowsiness, or fainting.
  • Pale or blue lips, fingernails, or skin.
  • Shortness of breath, or irregular, fast, slow, or shallow breathing.
  • Sores or white patches on your lips, mouth, or throat.
  • Unusual tiredness or weakness.

If you notice these less serious side effects, talk with your doctor:

  • Change or loss of taste.
  • Constipation or nausea.
  • Dry mouth.
  • Headache.
  • Increased sweating.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last reviewed on 6/12/2013

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