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Overview: Pentazocine/naloxone is an oral tablet used to treat moderate to severe pain when other treatments are not helping enough. Pentazocine works to help you feel less pain, while the naloxone ingredient helps to prevent misuse. Common side effects include constipation, nausea or vomiting, headache, and drowsiness. Tell your health care provider right away if you feel confused or your pain is getting worse instead of better. Get emergency help right away if you have trouble breathing or severe sleepiness.

Uses

What is pentazocine/naloxone used for?

Pentazocine/naloxone is an opioid medicine that is commonly used to treat moderate to severe pain when other treatments are not helping enough. 

Pentazocine/naloxone may also be used for other conditions as determined by your health care provider.

How does pentazocine/naloxone work (mechanism of action)?

This product contains two medicines, pentazocine and naloxone. Pentazocine is a type of opioid that works on certain receptors in your brain and nervous system to help ease pain. Naloxone is an opioid blocker that has no effect when taken by mouth but helps prevent misuse if this combination medicine is injected. 

How is pentazocine/naloxone supplied (dosage forms)?

Brands and other names

  • Talwin NX

Dosage forms and strengths

  • 50 mg/0.5 mg oral tablets

How should I store pentazocine/naloxone?

Pentazocine/naloxone should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a tightly closed container in a cool, dry place.

Side Effects

What are the most common side effects of pentazocine/naloxone?

The most common side effects of pentazocine/naloxone are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Constipation
  • Nausea or vomiting
  • Drowsiness and tiredness
  • Headache
  • Dizziness
  • Stomach pain

There may be other side effects of pentazocine/naloxone that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of pentazocine/naloxone?

While less common, the most serious side effects of pentazocine/naloxone are described below, along with what to do if they happen.

Severe Allergic Reactions. Pentazocine/naloxone may cause allergic reactions, which can be serious. Stop taking pentazocine/naloxone and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Central Nervous System (CNS) Effects. Pentazocine/naloxone may slow down your central nervous system (CNS), which controls many vital functions throughout the body. It can also have other effects on your CNS. Call your health care provider right away if you have any of the following symptoms.

  • Confusion or feeling disoriented
  • Excessive sleepiness or trouble staying awake
  • Memory problems
  • Slow or shallow breathing
  • Slowed response or reaction time
  • Slurred speech
  • Seeing or hearing things that others do not see or hear, also called hallucinations
  • Feeling dizzy

Risk of Misuse and Addiction. Misuse means taking a medicine in a way other than how it was prescribed. Misuse of pentazocine/naloxone can lead to serious side effects or death. Take pentazocine/naloxone exactly as prescribed. Tell your health care provider if you feel that pentazocine/naloxone is not working. Call your health care provider right away or go to the nearest emergency room if you have any of the following serious symptoms.

  • Sudden confusion or feeling disoriented
  • Feeling paranoid
  • Suicidal thoughts or actions
  • Trouble breathing

Breathing Problems. Pentazocine/naloxone may cause slow or shallow breathing, even if it is taken as prescribed. This risk may be higher if you have breathing problems from another condition, take other medicines that can slow your breathing, or are older. Tell your health care provider if you have severe sleepiness or trouble breathing, especially when you start pentazocine/naloxone or when your dose is increased. Get emergency help if you have any of the following symptoms.

  • Slow or shallow breathing
  • Changes in the color of your skin, including bluish color to your lips and fingernails
  • Shortness of breath
  • Feeling dizzy, lightheaded, or fainting
  • Changes in your heart rate or rhythm, such as a fast, slow, pounding or skipping heartbeat
  • Excessive sleepiness or trouble staying awake

Increased Pain and Pain Sensitivity. Pentazocine/naloxone may cause allodynia, which is when you have pain from something that normally does not cause pain, such as brushing your hair. Pentazocine/naloxone may also cause hyperalgesia, which is when you are very sensitive to pain. Contact your health care provider right away if you have pain from things that did not cause pain before, worsening pain, or more pain sensitivity. Do not take more pentazocine/naloxone if your pain feels worse as this may cause serious side effects.

Low Blood Pressure (Hypotension). Pentazocine/naloxone may cause low blood pressure. It may also cause a sudden drop in blood pressure when standing up from a seated or lying position. To help prevent this, be careful not to get up too quickly. If you feel faint or dizzy, lie down. Tell your health care provider right away if you have any of the following symptoms of low blood pressure.

  • Dizziness, feeling lightheaded, or fainting
  • Feeling weak or tired
  • Sudden dizziness or trouble seeing when you stand or sit up

Reduced Adrenal Function. Long-term use of pentazocine/naloxone can cause adrenal insufficiency, which is when your body’s adrenal glands stop making as much cortisol (the stress hormone). Adrenal insufficiency can worsen if your body is under stress because of fever, surgery, or trauma. Tell your health care provider if you have any of the following symptoms of adrenal insufficiency.

  • Nausea, vomiting, or loss of appetite
  • Weakness, tiredness, or lack of energy
  • Low blood pressure or dizziness

Warnings & Precautions

Who should not use pentazocine/naloxone?

Allergies to Ingredients. People who are allergic to any of the following should not take pentazocine/naloxone.

  • Naloxone
  • Pentazocine
  • Talwin NX
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific pentazocine/naloxone products they stock.

Breathing Problems. Pentazocine/naloxone should not be taken if you have severe asthma, trouble breathing, or other lung problems.

Gut Blockage. Pentazocine/naloxone should not be taken if you have a blockage of your gut (bowel obstruction) or a narrowing of your stomach or intestines.

What should I know about pentazocine/naloxone before taking it?

Do not take pentazocine/naloxone unless it has been prescribed to you by a health care provider. Take it exactly as prescribed. Read and follow the instructions that come with your medicine.

Do not share pentazocine/naloxone with other people, even if they have the same condition as you. It may harm them.

Keep pentazocine/naloxone out of the reach of children. Taking pentazocine/naloxone by accident can lead to serious side effects, including breathing problems or death.

Pentazocine/naloxone is a controlled substance because it can be misused or lead to dependence. It is illegal to sell or give away this medicine. Store pentazocine/naloxone in a safe place where other people cannot take it. This is especially important if someone in your home has a substance use disorder or has had past problems with drug misuse. 

Do not change your dosage of pentazocine/naloxone without checking with your prescriber. Tell your health care provider if you feel that pentazocine/naloxone is not working or if your pain feels worse or different than usual.

Pentazocine/naloxone can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how pentazocine/naloxone affects you.

People who are 65 years and older can be at greater risk of some side effects from pentazocine/naloxone. Talk to your health care provider about your risks if you are in this age group. 

Constipation is a common side effect of pentazocine/naloxone, and it can sometimes be severe. Ask your pharmacist or other health care provider how to prevent constipation or treat it if needed.

Talk to your health care provider about whether you should keep rescue naloxone with you. Naloxone is a medicine that is used for the emergency treatment of an opioid overdose. The naloxone in pentazocine/naloxone will not treat an opioid overdose.

Pentazocine/naloxone is usually prescribed for short-term pain relief. But if you have been taking pentazocine/naloxone for more than a few weeks, do not stop taking it without talking to your health care provider. They can guide you on how to stop it safely. Suddenly stopping pentazocine/naloxone may cause severe withdrawal symptoms. Call your health care provider right away if you have any of the following symptoms.

  • Sweating more than usual
  • Shaking 
  • Feeling hot or cold
  • Runny nose
  • Watery eyes
  • Goosebumps
  • Vomiting or diarrhea
  • Muscle aches
  • Changes in mood or behavior

Taking pentazocine/naloxone for a long time may affect your ability to become pregnant or get a partner pregnant. Tell your health care provider if you have any concerns about this.

Throw away any unused pentazocine/naloxone right away. If a local drug take-back site is not available, you can flush it down the toilet. 

What should I tell my health care provider before taking pentazocine/naloxone?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if pentazocine/naloxone is right for you.

In particular, make sure that you discuss any of the following.

Other Medicines and Supplements. Pentazocine/naloxone may interact with other medicines and supplements. Before taking pentazocine/naloxone, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Smoking. Smoking tobacco can make pentazocine/naloxone not work as well. Tell your health care provider if you smoke. 

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

Pregnancy. Taking pentazocine/naloxone while pregnant may cause withdrawal symptoms in your newborn baby (neonatal opioid withdrawal syndrome). This condition can be life-threatening if not properly treated. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. Pentazocine/naloxone passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take pentazocine/naloxone while breastfeeding.

Interactions

Does pentazocine/naloxone interact with foods or drinks?

There are no known interactions between pentazocine/naloxone and foods.

Do not drink alcohol or take any prescription or over-the-counter (OTC) medicines containing alcohol while you are taking pentazocine/naloxone. Combining alcohol and pentazocine/naloxone raises the risk of breathing problems and other serious side effects. 

Does pentazocine/naloxone interact with other medicines (drug interactions)?

Always tell your health care provider about any prescriptions or over-the counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking pentazocine/naloxone.

  • A benzodiazepine, such as clonazepam (Klonopin), diazepam (Valium and others), or lorazepam (Ativan and others), which is a medicine used for anxiety, muscle spasms, or seizures
  • A muscle relaxant, such as carisoprodol (Soma), cyclobenzaprine, metaxalone, or tizanidine (Zanaflex)
  • Any other medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, or medicines for anxiety
  • A selective serotonin reuptake inhibitor (SSRI), such as fluoxetine, paroxetine, or sertraline, which is a medicine commonly used for anxiety and depression
  • A serotonin and norepinephrine reuptake inhibitor (SNRI), such as duloxetine or venlafaxine, which is a medicine commonly used for anxiety and depression
  • A tricyclic antidepressant, such as amitriptyline, nortriptyline, or protriptyline, even if it is not used for depression
  • A monoamine oxidase inhibitor (MAOI) within the past two weeks, which is a medicine usually used for depression or Parkinson’s disease
  • Any other medicine that affects serotonin, such as some medicines used to treat depression, anxiety, migraine, or nausea and vomiting
  • An antipsychotic, which is a medicine for certain mental health conditions
  • Any other opioid, such as codeine, fentanyl, morphine, or oxycodone, which is a medicine used to treat certain types of pain
  • A mixed agonist/antagonist or partial agonist opioid analgesic, such as buprenorphine (Butrans, Sublocade) and butorphanol, which are medicines used to treat certain types of pain or opioid use disorder
  • A diuretic, also called a water pill, which is a medicine used to reduce edema (fluid retention) and blood pressure
  • An anticholinergic medicine, which includes antihistamines and medicines commonly used for overactive bladder, Parkinson’s disease, or stomach problems

This may not be a complete list of medicines that can interact with pentazocine/naloxone. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much pentazocine/naloxone?

If you or someone else has taken too much pentazocine/naloxone, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222. 

It is also important to have rescue naloxone on hand in case of an opioid overdose. Be sure that you and your family, caregivers, and friends know how to recognize an opioid overdose and when and how to use rescue naloxone. See the Warnings & Precautions section for more details.

What should I do if I miss a dose of pentazocine/naloxone?

If you miss a dose, take the next dose at your usual time. Do not take double or extra doses.