Some unwanted side effects caused by Fentanyl

In addition to its required benefits, some unwanted effects can be caused as a result of using Fentanyl. These side effects need immediate medical attention to avoid further complications.

Let us look at some major side effects that are noticed as a result of Fentanyl and need immediate medical attention

More common

  • Chest pain
  • Confusion
  • Cough
  • Dizziness
  • Tarry or black stools
  • Decreased urine
  • Dry mouth
  • Fainting
  • Chills or fever
  • Increased thirst
  • Difficulty in breathing
  • Appetite loss
  • Lightheadedness
  • Mood changes
  • Side or lower back pain
  • Vomiting
  • Nausea
  • Muscle cramps or muscle pain
  • Tingling or numbness in hands, lips and feet
  • Sneezing
  • Pale skin
  • Nervousness
  • Sunken eyes
  • Rapid breathing
  • Exertion and troubled breathing
  • Chest tightness
  • Unusual bruising or bleeding
  • Unusual weakness and tiredness
  • Sores, white spots or ulcers in mouth
  • Wrinkled skin


Less common

  • Thinking abnormalities
  • Severe sleepiness
  • Shakiness in feet, hands, arms and legs
  • Shaking or trembling feet or hands
  • Seizures
  • Muscle jerking or twitching
  • Unsteadiness and clumsiness
  • Change in balance or walking
  • Stomach or abdominal pain
  • Headache
  • Decreased responsiveness or awareness
  • Decreased urination
  • Unsteadiness or clumsiness
  • Severe constipation

Symptoms of overdose

  • Slow breathing or shallow breathing

If you notice any of the above symptoms of overdose while using Fentanyl, ask for emergency medical help immediately.

Side effects- Minor

Some side effects do not need medical help. As your body gets used to the medication, these side effects disappear with time. Your physician can tell you how to reduce the side effects and if any of these side effects continue for a longer period, contact your health care provider immediately. More common side effects are

  • Diarrhea
  • Irritability
  • Feeling empty or sad
  • Back pain
  • Tiredness
  • Loss of pleasure or interest
  • Joint pain
  • Unusual drowsiness
  • Weight loss
  • Trouble sleeping
  • Discouragement
  • Difficult in bowel movement
  • Muscle stiffness

Less Common side effects are

  1. Increased muscle tone
  2. Feeling heat or warmth
  3. Sweating
  4. Rash
  5. Itching skin
  6. Spinning sensation
  7. Redness or flushing of skin on neck or face


Post treatment- Side effects

After you stop using Fentanyl, you might experience side effects that need medical help. If you notice the side effects given below, contact your doctor immediately

  1. Weakness
  2. Stomach cramps
  3. Restlessness
  4. Speech disorder

Side effects can range from mild to severe, but if you think that they are troublesome, please seek medical help as some side effects if not treated in time can be life threatening too. Talk to your doctor to know about the possible side effects of the drug, so that it becomes easy for you to identify possible side effects and call for medical help if required.

With benefits Fentanyl also has side effects that might need change in dose. Your doctor is the right person to adjust your dose and help you use the medication safely.

Right dosage of Fentanyl can be helpful

Learning about the right dosage of Fentanyl can be helpful for you. Let us learn about the right dosage of Fentanyl so that it becomes easy for you to avoid overdose and related complications

Dosage strengths and forms

Surgery premedication

50-100 mcg/dose or IV (slow) of minimum 30 to 60 minutes before surgery

Addition to regional anesthesia- 24-100 mcg/dose or IV (slow) above 1-2minutes

General Anesthesia

Surgical procedures (minor) – 0.5 to 2 mcg/kg/dose IV

Chronic Pain (Severe)

To be used in patients tolerant to opioid for treating chronic pain. Daily doses, long term treatment through opioids are required for severe pain in case there are no alternative treatments available.


Due to the risk of abuse, addiction and misuse of opioids even in case of recommended doses and due to high risk of overdose and death with the use of extended release formulation of opioid,  limited to patients whom no other alternative          treatment method is effective, not tolerated or in cases where sufficient management of pain is not achieved.

Dosing restrictions

It is not recommended to treat acute pain or used as PRN analgesic


Treating overdose of Fentanyl

Treatment for overdose of Fentanyl should be started immediately, upon knowing that overdose has taken place. If the overdose occurs due to lozenge or patch, then the very first step should be flushing out Fentanyl and stop the absorption of Fentanyl in the body. This is where the medical professional consider Fentanyl as a strong poison.

Depending upon when Fentanyl dose was consumed last, user’s stomach is pumped to eliminate the drug that is being absorbed in the bloodstream. Activated charcoal is used to flush out the drug from the bloodstream. It helps preventing the damage caused due to absorption of drug in large amounts. If you notice someone losing consciousness suddenly and appear to be sleeping peacefully, it can be overdose symptoms that you cannot ignore. If you cannot manage to get antagonist drugs, turn the patient on one side and sometimes the patient vomits to throw out the medicine.

Overdose can happen in people who use this drug to get instant pain relief and as Fentanyl is quite effective in treating pain faster, people tend to depend on the drug or fall in prey for overdose. It is recommended that one should take Fentanyl in right doses as prescribed by the doctor.

The medication is strong enough to cause life threatening damage and to avoid such a situation; you need to be very careful about drug dependency. There are many rehabilitation centres that help people who get are victims of drug abuse to overcome addicition. To prevent Fentanyl overdose, you can educate yourself on the right dosage of Fentanyl.

You can ask your doctor for a suitable dose and if possible do not take Fentanyl for a long term or in high doses. Discuss with your doctor about other medications that you are using along with Fentanyl to avoid complications. Fentanyl drug interactions can also lead to overdose, which can be avoided by following your doctor’s instructions.

Fentanyl drug interactions that you might not be aware about

Some medicines can lead to dangerous and unwanted effects when taken with Fentanyl.  Tell your physician about all other medication you are using or medications that you started or stopped using.

After taking Fentanyl, using other drugs that make you feel drowsy or slow breathing can be quite dangerous and fatal too. Check with your doctor before you take pain medicine (narcotic), sleeping pill, medicines for seizures, depression or muscle relaxer.

Even other medications like OTP drugs, vitamins, herbal supplements can also interact with Fentanyl. So make sure you discuss with your doctor about the medicines that you are using now.

Let us have a look at some other Fentanyl drug interactions


Using Lorazepam and Fentanyl together can increase unwanted side effects like drowsiness, confusion, dizziness and breathing problems. Elderly people often experience impairment in judgment and thinking as well as motor co-ordination. Also you should avoid alcohol consumption while you are on these medications. Avoid engaging yourself in activities that need extra alertness and need you to be awake till the time you know how medication works for you.


Taking Fentanyl and Pregabalin together can lead to side effects like confusion, drowsiness, dizziness and difficulty in concentrating. Elderly people experience impairment in motor co-ordination, judgment etc.


Using Fentanyl and duloxetine together can lead to rare yet serious condition termed as  serotonin syndrome, that can result in symptoms like




Excessive sweating

Changes in blood pressure

Stomach cramp



Blurred vision


Sometimes in severe cases it can lead to coma or death. If you experience such symptoms while using these medications together, contact your health care provider immediately.

Fentanyl- furosemide

Fentanyl and Furosemide can have additional effects in decreasing your blood pressure. You may notice fainting, lightheadedness, headache, change in heart or pulse rate or dizziness. These side effects are observed in initial stages of treatment followed by an increase in dose or when the treatment is started again after a period of time. Do not operate hazardous machinery until you know the effects of medication.

It is always better to let your doctor know about the medication you are using as you are not aware about the possible drug interactions of Fentanyl. To be on the safer side consult your doctor. Checking the ingredients present in all other medications you are using can help you avoid drug interactions.

Avoid consuming alcohol with Fentanyl as it can lead to serious side effects. Alcohol consumption with Fentanyl can affect your nervous system and lead to difficulty in concentrating, low BP, lightheadedness, impairment in judgment and thinking ability. Also do not consume grapefruit juice or grapefruit as these increases the blood levels and efficacy of Fentanyl.

Avoid activities that need mental alertness as Fentanyl leads to drowsiness and dizziness. Once you know how your body reacts to Fentanyl, you can engage in activities that require mental alertness, only if you do not experience severe drowsiness, dizziness etc.

Always check with your doctor about the side effects and drug interactions so that Fentanyl doesn’t harm you.

Facts to be considered while using Fentanyl

Fentanyl is basically an opioid medication and an opioid medication is sometimes termed as narcotic. Fentanyl is used as a form of anesthesia to prevent pain after any medical procedure or surgery.

Generic Name Fentanyl

Brand Name: Sublimaze

You should not use Fentanyl if you are allergic to this medication or any other narcotic drug. It is necessary for your doctor to monitor you when getting Fentanyl injection. This will help your doctor decide whether the medication is working for you or not and if you can continue with the treatment.

Consult your doctor immediately if you see the following symptoms in your child after getting Fentanyl.

  1. Bluish skin, lips
  2. Breathing problems
  3. Chest pain
  4. Irregular, fast heartbeat
  5. Irregular pulse
  6. Breathlessness
  7. Muscle stiffness

Important information

Some medicines interact with Fentanyl and it can lead to a serious medical condition called serotonin syndrome. Make sure you tell your doctor if you are taking other medications for mental illness, depression, migraine headaches, Parkinson’s disease, serious infections or medicines to prevent vomiting or nausea. Consult your physician before making any changes to the medications prescribed by him.

To know if Fentanyl is a safe drug for you, let your doctor know if you have the following health ailments

  1. Kidney or liver disease
  2. Lung problem or Breathing problem
  3. History of brain tumor or head injury.
  4. If you have tried using an MAO inhibitor in last 14 days.


Fentanyl injection

Fentanyl is directly injected into your muscle or vein or via IV. Your physician will give you Fentanyl injection as a form of anesthesia for any medical procedure or surgery. While receiving Fentanyl injection, your breathing, oxygen levels and blood pressure will be monitored closely.

You doctor might give you some other drugs to use after Fentanyl treatment is gets over.

Fentanyl can lead to side effects that can affect your reactions or thinking. Avoid driving or any other activity that needs you to be alert and awake immediately after you are given Fentanyl treatment. Severe drowsiness or dizziness can lead to accidents or falls. Follow the instructions of your doctor about other restrictions related to beverages, food or activity.

Is Fentanyl addictive?

Since Fentanyl works very quickly to eradicate pain in the body, it can be addictive. Fentanyl is used frequently in hospitals and people who have access to Fentanyl can fall in prey to addiction of this drug. Other start taking Fentanyl as prescribed by the doctor, but later become dependent on the drug.

When a person is using Fentanyl for a long period, he/she can experience various severe side effects. It can result in both physical and mental side effects. These symptoms of drug abuse needs to be treated to avoid lifetime complications. The treatment includes detox as Fentanyl is both psychologically and physically addictive. There are various unpleasant withdrawal symptoms that an addictive person may experience as a result of quitting drug.

One should be careful and use Fentanyl carefully as it is highly addictive and can lead to several problems.

During pregnancy and breastfeeding- Is Fentanyl safe to use?

During pregnancy and breastfeeding, a woman goes through a period of complete change as she is takes care of her baby during this phase. There are so many hormonal changes that make her excited, feel low and sometimes depressed. Apart from these hormonal changes, she also goes through pain, depression etc.; to treat pain she is often dependent on drugs that can help relieve pain. Using drugs during pregnancy and breastfeeding can be risky too. Fentanyl is also an opioid that have adverse effects if used for a long term during pregnancy or breastfeeding. Let us see how it effects your pregnancy or breastfeeding phase.

Fentanyl and Pregnancy

Prolonged use of Fentanyl during pregnancy can lead to drug dependency in new born. It can also cause neonatal opioid withdrawal syndrome, which comprises of various signs and symptoms like

  1. Rigidity
  2. Irritability and poor feeding
  3. Seizures or tremors
  4. Diarrhea

Studies conducted on animal pregnancy show that Fentanyl can have negative effect on fetus, so there are chances that Fentanyl can harm growing human fetuses too.

You should use Fentanyl during pregnancy only if the pain relieving benefits are higher than the possible risks to the fetus. Fentanyl should be avoided during pregnancy or before delivery because opioids can lead to respiratory depression in newborn babies.

Fentanyl and Breastfeeding

Fentanyl is included in the list of drugs that are suitable during breastfeeding. Some experts ask mothers not to discontinue breastfeeding if Fentanyl is necessary for them after birth of their babies, but they should monitor for any changes in infant development, especially weight curve, maturation, neuromotor and alertness.

If possible, Fentanyl dose should be reduced and complimented it with alternative non narcotic medicines.

As per manufacturers warning, Fentanyl gets secreted into breast milk, which can lead to shallow breathing and extreme drowsiness in your baby. Speak to your doctor to know if Fentanyl is safe while breastfeeding and you can continue with Fentanyl dose only if your doctor feels it has more benefits than risks for you and your baby.

Some women undergo surgical procedure after their delivery and they need to take anesthesia and in such cases doctor recommend low doses of Fentanyl so that it doesn’t lead to any complications. Both opioid or pain killers can have adverse effects on breastfeeding, therefore mothers should be advised to use lowest dose to treat pain as lowest dose is quite effective. Fentanyl can harm babies’ suckling vigor and alertness.

So try to use alternative medicines to control pain instead of taking Fentanyl frequently in high doses. Mothers can use other medicines that are equally effective to treat pain and doesn’t affect breastfeeding. Opioids can be harmful for the baby if you are using it in high doses and for a long term, so avoid using it while breastfeeding or consult your doctor for the right dosage. Your doctor can advice you on whether you need Fentanyl or not or can continue to take in low doses.

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