On this page · 9 sections

Fentanyl (buccal/sublingual)

Generic name: fentanyl (buccal/sublingual)

Brand names: Subsys

Last updated November 2, 2026 0 views
Share

What is fentanyl buccal/sublingual?

Fentanyl buccal or sublingual products are used in the mouth but should not be swallowed whole. Fentanyl buccal is placed in the mouth between the cheek and gum. Fentanyl sublingual is placed under the tongue.

Fentanyl buccal/sublingual is an opioid pain medicine used to treat "breakthrough" cancer pain that is not managed by other medicines. Fentanyl is not for treating pain that is not related to cancer.

Fentanyl buccal/sublingual may also be used for other purposes not mentioned in this medication guide.

This section was rewritten for readability and reviewed for meaning.

Warnings

MISUSE OF OPIOID MEDICINE CAN CAUSE ADDICTION, OVERDOSE, OR DEATH. Keep the medication in a place where others cannot get to it.

Do not use fentanyl unless you are already using an around-the-clock opioid medicine and are tolerant to it.

Taking opioid medicine during pregnancy may cause life-threatening withdrawal symptoms in the newborn.

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

This section was rewritten for readability and reviewed for meaning.

Before taking this medicine

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

  • severe asthma or other breathing problems; or
  • a stomach or bowel obstruction (including paralytic ileus).

Tell your doctor if you have ever had:

  • breathing problems, sleep apnea;
  • a head injury, 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 opioid medicine 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 opioids may need medical treatment for several weeks.

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

This section was rewritten for readability and reviewed for meaning.

Fentanyl buccal/sublingual side effects

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

Opioid medicine can slow or stop your breathing, and death may occur. 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.

Fentanyl may cause serious side effects. 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 side effects of fentanyl 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.

This section was rewritten for readability and reviewed for meaning.

How should I use fentanyl buccal/sublingual?

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

Follow the directions on your prescription label and read all medication guides. Never use fentanyl in larger amounts, or for longer than prescribed. Tell your doctor if you feel an increased urge to take more of fentanyl.

Never share opioid medicine with another person, especially someone with a history of drug abuse or addiction. MISUSE CAN CAUSE ADDICTION, OVERDOSE, OR DEATH. Keep the medication in a place where others cannot get to it. Selling or giving away opioid medicine is against the law.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.

Call your doctor if you have breakthrough pain more than 4 times in one day while using this medicine. Do not treat more than 4 pain episodes per day with this medicine.

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

Never crush or break a fentanyl pill 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 your medicine. You should be aware if anyone is using it improperly or without a prescription.

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

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 fentanyl tablets by removing them from the blister pack and flushing them down a toilet. Dispose of used sublingual spray units in the disposal bags provided with the medicine. Empty any unused spray units into the disposal bottle provided.

What happens if I miss a dose?

Since fentanyl is used for pain, you probably won’t miss a dose. If you do miss a dose and it’s almost time for your next dose, skip the missed dose. Do not use two doses at one time.

This section was rewritten for readability and reviewed for meaning.

What happens if I overdose?

Seek emergency medical help or call the Poison Help line at 1-800-222-1222. A fentanyl overdose can be deadly, especially in a child or anyone using the medicine without a prescription. Overdose symptoms may include extreme weakness or sleepiness, weak pulse, cold and sweaty skin, small pupils, and slow breathing (breathing may stop).

Avoid driving or doing anything dangerous until you know how fentanyl will affect you. Dizziness or sleepiness can lead to falls, accidents, or serious injuries.

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

Grapefruit may interact with fentanyl and cause unwanted side effects. Stay away from grapefruit products.

This section was rewritten for readability and reviewed for meaning.

What other drugs will affect fentanyl buccal/sublingual?

You may have breathing problems or withdrawal symptoms if you start or stop taking certain other medicines. Tell your doctor if you also use an antibiotic, antifungal medication, heart or blood pressure medication, seizure medication, or medicine to treat HIV or hepatitis C.

Opioid medication can interact with many other drugs and cause dangerous side effects or death. Make 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 affect fentanyl, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

This section was rewritten for readability and reviewed for meaning.

Common questions about fentanyl

What drugs cause pinpoint pupils?
Pinpoint pupils, medically termed miosis, refer to abnormally small, constricted pupils that do not dilate appropriately in low light. This symptom can be caused by opioids, clonidine, buspirone, metoclopramide, and other medications. Continue reading
Which drugs cause opioid-induced constipation?
Any drug that is classified as an "opioid" can cause constipation, which can be a serious side effect if not addressed. Examples of commonly prescribed opioids that may cause this side effect include morphine, tramadol, fentanyl, methadone, hydrocodone, codeine and oxycodone. Continue reading
How long does Fentanyl stay in your system?
Traces of fentanyl can stay in your system for a lot longer than it takes for the effects of fentanyl to wear off. Drug testing can detect fentanyl or its metabolites (breakdown products) in urine for 24 to 72 hours, in blood for 5 to 48 hours, and in hair for up to 3 months, but it cannot be consistently detected in saliva. Continue reading
Carfentanil vs Fentanyl: Which is more dangerous?
Both illegally-made fentanyl and carfentanil are extremely dangerous opioids that may result in a quick overdose and death when abused, but carfentanil is more potent than fentanyl. Multiple doses of the anti-overdose drug naloxone (Narcan) or nalmefene (Opvee) may not be effective to reverse an overdose. Continue reading
Fentanyl test strips: where to get & how to use?
Fentanyl test strips can be found at your local health department, at a community needle-exchange program, from reliable online sources, or even vending machines in some states. Once the strip is dipped into a sample of the drug (usually dissolved in a small amount of water), the results indicate if fentanyl is present. Follow the instructions for use on your specific test strips. Continue reading
Why is fentanyl so dangerous?
Fentanyl is a powerful opioid that can be deadly when misused or taken in an overdose. It can quickly slow or stop breathing, especially in people who are not used to its effects. Combining fentanyl with alcohol, benzodiazepines, gabapentinoids, other opioids, or other depressants greatly increases the risk of overdose and death. Continue reading
What are the symptoms of a fentanyl overdose?
Illicit Fentanyl, a potent synthetic opioid, is a leading cause of U.S. overdose deaths. Often mixed with other drugs, it can rapidly depress breathing and cause death. Recognizing overdose signs like extreme drowsiness, slowed breathing, constricted pupils, cyanosis (blue lips, skin, fingernails), seizures, or coma is critical for timely emergency intervention. Continue reading
How does fentanyl compare to heroin or other opiates?
Fentanyl is an extremely potent, synthetic (man-made) opioid, and is about 50 times more potent than heroin and 100 times more potent than morphine. Fentanyl is a legally prescribed drug for pain in the U.S. and is classified as Schedule II controlled substance when used for legitimate medical purposes. In contrast, heroin is 2 to 3 times more powerful than morphine. Heroin is illegal in the U.S. and is classified as a Schedule I controlled substance. Continue reading

Related medicines

Before you take this medicine: the information on this page is general and may not cover your personal circumstances. Read the label supplied with your medicine and ask a pharmacist or doctor if you are unsure, especially if you are pregnant, breastfeeding, taking other medicines or managing a long-term condition.
General medicine information Consumer-friendly language

Content is provided for education and is not medical advice. See our medical disclaimer.