Pentazocine (Injection)

Pentazocine belongs to a family of drugs known as 'œnarcotic analgesics', and is used to treat moderate to severe pain, and as an anesthetic.


Pentazocine is believed to relieve pain by acting on the central nervous system, attaching to opioid receptors. For this reason, it is also classified as an opioid.

As well as the treatment of pain, pentazocine is also used as a general anesthetic (a medication that puts you to sleep) before surgery.

Like other opioids, this medication is known to produce a variety of side effects, such as itching, nausea, constipation, and difficulty breathing. It can also trigger hallucinations (seeing things that are not there) in some people.

Also in common with other opioids, pentazocine has the potential for dependence. Although addiction is less common when people take the drug solely for the purpose of reducing pain caused by another condition, physical dependence and withdrawal symptoms can occur when people stop taking the drug. Therefore, patients are normally advised to reduce the dose of the medication gradually rather than abruptly ceasing its use.

In the US, pentazocine is commonly sold under the brand name 'œTalwin'.

Conditions Treated

  • Moderate to severe pain
  • Labor pain
  • Used as an anesthetic or sedative

Type Of Medicine

  • Narcotic analgesic
  • Opioid
  • Benzomorphan
  • Anaesthetic

Side Effects

As well as its desired effect of relieving pain, pentazocine can sometimes trigger some undesired side effects. Serious side effects are rare, but they have occurred in some individuals. Consult the doctor or nurse on duty immediately if you notice any of the symptoms listed below:

  • Black, tarry stools
  • Bleeding or bruising
  • Blue or pale lips, fingernails or skin
  • Blurred vision
  • Chills
  • Confusion or disorientation
  • Coughing fits
  • Depression
  • Diarrhea
  • Difficulty breathing
  • Difficulty or pain when urinating, or reduced volume of urination
  • Dizziness
  • Faster heartbeat, 'œpounding' in the chest, irregular heartbeat
  • Feeling faint or lightheaded
  • Fever
  • Hardness or thickening of the skin
  • Headache
  • Irritation or redness in the eyes
  • Itching
  • Nervousness
  • Numbness
  • Pain in the chest
  • Pain in the joints
  • Pain in the muscles
  • Pain, stinging, redness, or small lumps at the site of the injection
  • Peeling or blistering of the skin
  • Pins and needles or tingling of the skins
  • Pounding or pain in the ears
  • Shaking or trembling arms, legs, hands, or feet
  • Skin color changes, particularly a blue-green or black coloration
  • Skin lesions, especially red with a purple center
  • Slower heart rate/pulse
  • Sore throat
  • Sores, ulcers, white spots or lesions on the lips or mouth
  • Sweating excessively
  • Swelling in the face or glands
  • Tiredness, fatigue, or weakness
  • Very slow breathing rate
  • This medication may also trigger other side effects that are less serious but may be bothersome or concerning to you. The most common of these include:
  • Increase feeling of well-being or happiness
  • Nausea or vomiting

Less common side effects include:

  • Changes in taste
  • Constipation
  • Double vision, blurry vision, or difficulty focusing
  • Difficulty hearing or hearing loss
  • Difficulty sleeping
  • Drowsiness
  • Dry mouth
  • Excitement
  • Hallucinations -- seeing, hearing, or feeling things that are not there
  • Irritation
  • Mental confusion, for example now knowing where you are or what time it is
  • Relaxation and calmness
  • Ringing in the ears
  • Sleepiness or tiredness
  • Small pupils (the black part of the eye)
  • Stomach cramps
  • Sweating
  • Twitching or 'œshaking' in the eyes; uncontrolled eye movements
  • Weakness or fatigue

This is not an exhaustive list of the potential side effects that may be experienced when taking pentazocine. Pay attention to how you feel when you are taking this medication. In some cases, side effects are not serious and will pass with time, however, in other cases they may need medical attention. If you notice any concerning or unusual side effects, inform the doctor or nurse immediately.


Overdoses of pentazocine can cause very serious side effects and can be fatal. For this reason, the injectable versions of this medication will only be dosed and administered by medical professionals in a hospital. If an overdose were to occur, however, the potential symptoms could include the following:

  • Coma
  • Extreme disorientation, clumsiness or confusion
  • Extreme drowsiness, fatigue or sleepiness
  • Irregular heartbeat
  • Reduced body temperature
  • Rigid muscles
  • Muscle spasms
  • Vomiting
  • Weak pulse
  • Allergic reaction

Allergic reactions to pentazocine are rare, but they have been reported. This medication will normally only be administered in a hospital or other facility with staff and equipment suitable for dealing with such reactions. Inform the doctor or nurse if you notice any of the following symptoms:

  • Difficulty in breathing, including wheezing
  • Hives, rashes, or redness on the skin
  • Itching
  • Swelling, especially of the face, tongue, or throat
  • Severe coughing
  • Severe dizziness, disorientation, drowsiness, or fatigue


The amount of this drug that you are given will be unique to you, and will depend on factors such as your body weight, the particular condition that you suffer from, the severity of your symptoms, your medical history, and whether you are taking any medications that can interact with pentazocine.

Your dose will be determined and administered to you in a hospital by a nurse, doctor or other medical professional via an injection. The location of the injection can be under the skin (subcutaneous), into a muscle (intramuscular), or into a vein (intravenous).

Typically, the dose administered to adults will be 30 mg, and this may be repeated every 3 to 4 hours while under medical supervision. Higher doses are sometimes given, although the maximum that is normally given in a single dose is 30 mg intravenously, and 60 mg intramuscularly or subcutaneously. Under normal circumstances, the total daily dose would not exceed 360 mg. In children, the typical dose is 0.5 mg per kg of bodyweight via the intramuscular route.

Older people may be more sensitive to the effects of pentazocine than younger individuals. They also on average tend to have more kidney issues than younger populations. If you are over the age of 65, you will probably be prescribed a lower dose of pentazocine, and your doctor may want to see you regularly to ensure that the medication is not producing any harmful side-effects.

In most cases, you will start your treatment with the injected version of the drug, and later switch to oral tablets after your condition has improved.

The effect of this medication can have 'a œceiling effect', which is to say, no further therapeutic effects will be achieved beyond a certain dose. If you notice that further doses of the drug are producing no additional effects, inform the doctor or nurse in charge of your care. Beyond the ceiling, additional doses will not improve your symptoms but they may increase the risk of adverse side effects.

Pentazocine can cause withdrawal effects when you stop taking it. These include:

  • Anxiety
  • Desire to continue taking the medication
  • Difficulty sleeping
  • Headaches
  • Fever
  • Nausea
  • Runny nose
  • Stomach cramps
  • Sweating
  • Tremors

When you approach the end of your course of treatment with this drug, your dose will normally be reduced gradually over the course of a few weeks, rather than abruptly stopping the use of the medication. This will help to minimize the withdrawal symptoms that you experience, however you may still experience some symptoms when you stop taking the drug completely.


Some medications can interact with pentazocine in ways that produces adverse or harmful side effects. Before taking pentazocine, you should discuss with your doctor any medications, herbal products, vitamins or food supplements that you are presently taking.

Generally speaking, central nervous system depressants, recreational/street drugs, stimulants, painkillers, medications used to prevent or treat infections, and medications used to prevent nausea can be dangerous when taken along with pentazocine. Examples of some specific medications are medications listed below:

  • Acetaminophen (Paracetamol)
  • Atorvastatin (Lipitor)
  • Bupropion (Wellbutrin XL)
  • Butorphanol
  • Calcium
  • Cetirizine (Zyrtec)
  • Co-trimoxazole (sulfamethoxazole / trimethoprim)
  • Demerol (meperidine)
  • Duloxetine (Cymbalta)
  • Furosemide (Lasix)
  • Hydrocodone (e.g., Norco)
  • Magnesium
  • Mineral supplements
  • Morphine
  • Multivitamins
  • Naloxone
  • Niacin (Niaspan)
  • Oxcarbazepine (Trileptal)
  • Oxycodone (Percocet)
  • Promethazine
  • Quetiapine (Seroquel)
  • Thyroid desiccated (Armour Thyroid)
  • Tramadol
  • Tripelennamine
  • Vitamin B12 (cyanocobalamin)
  • Vitamin C (ascorbic acid)
  • Zolpidem (Ambien, or Ambien CR)
  • Zinc

Please note that this is not an exhaustive list and many other medications are known to interact with pentazocine. This is why it is important that your doctor is aware of all medications and over-the-counter products you are taking.

If you are taking any of the medications mentioned above, that does not necessarily mean you will not be prescribed pentazocine. However, the dosage of one or both medications may be adjusted, and your doctor will probably want to see you for regular tests to ensure that no unpleasant side effects are occurring.


This medication can be dangerous and even fatal when taken at the same time as alcohol. You should not consume alcohol while you are taking pentazocine. This includes other medications or products that contain alcohol. Combining these two drugs may cause symptoms such as:

  • Difficulty thinking or concentrating
  • Disorientation
  • Dizziness
  • Drowsiness
  • Lightheadedness
  • In much rarer cases, combining alcohol with pentazocine may cause:
  • Coma
  • Difficulty breathing
  • Fainting
  • Low blood pressure



Pentazocine is an opioid drug, and like all opioids it has the potential for dependence and addiction. There is also the potential for tolerance, in which your body adapts to the dosage you have been given and the pain-killing effect is lower than it previously was. If you notice that the medication is not working as well as it previously was, or if you are feeling urges to take the drug, let the doctor or nurse in charge of you know.


Pentazocine can act differently or can have a higher chance of producing side effects in people who have certain pre-existing medical conditions. Discuss your full medical history with your doctor before taking this medication. Conditions that are of particular concern include:

If you suffer from or have a history of any of these conditions, you may still be able to take pentazocine. However your doctor may want to adjust the dose, or they may want to see you more regularly for check-ups than they otherwise would.

Drug or alcohol dependence

Because of its potential to cause addiction and dependence, pentazocine is generally not recommended for use in people with a history of drug, alcohol or other substance abuse disorders. If you have suffered from such issues in the past but there is no alternative medication that you can take, your doctor will probably want to monitor you closely to ensure that symptoms of addiction can be managed.

Pentazocine can cause serious side-effects and even death when taken at the same time as alcohol. Therefore people who have a history of alcohol abuse may not be prescribed pentazocine, or they may be monitored closely to ensure no harmful side-effects have developed.


This medication can cause drowsiness, dizziness, disorientation and a lack of mental clarity. Do not operate heavy machinery or drive while you are taking this medication, unless you are sure that it is safe for you to do so.


Research has not yet determined whether this medication can safely be used by women who are breastfeeding. If you are breastfeeding or plan to be while you are taking pentazocine, discuss this with your doctor who will be able to advise you on the potential risks and benefits.


The safety and effectiveness of pentazocine in infants under 1 year of age has not been determined in appropriate studies. This medication should not be used in this age group without close supervision by a doctor.


The injectable solution of pentazocine will only be administered to you while you are in hospital and under the supervision of trained medical professionals. It is not likely that you would be given injectable pentazocine to take home with you and use yourself. Usually you would be given an oral form of the drug to use at home.

If medications are not stored properly, it may become less potent, or it may become harmful for you to take.

This medication should be stored at room temperature, and kept away from sources of heat such as heaters and radiators. The medication should also be kept away from sources of moisture and humidity - do not store medications in the bathroom because the moisture and heat created by the shower can damage them.

Keep the medication in the container that it came in, and do not store it near windows or any other location at which it will be exposed to direct sunlight.

Store this medication away from the sight and reach of children, in a child-safe container.

The medication should be disposed of safely through appropriate take-back or disposal centers. Do not flush the medication down the toilet or dispose of it in the regular trash.


Pentazocine is 'a œnarcotic analgesic' - a powerful painkiller used to treat moderate to severe pain.

It is an opioid, meaning that it comes with the potential for abuse and addiction. People who take this drug may feel a desire to continue taking it, and may experience withdrawal symptoms when the course of their treatment has finished. However, dependence is not common when individuals use the medication solely to relieve pain that they are experiencing due to another condition.

Many people who take pentazocine experience side effects of some kind, such as itching, nausea, headaches, and sometimes hallucinations. More serious side effects are rare, although they do occur, and potentially serious side effects or death can result from an overdose. Because of this, the injectable form of pentazocine is only administered in a hospital by trained medical professionals.

Pentazocine can cause harmful side effects when it is taken at the same time as certain other medications, primarily central nervous system depressants. You should always discuss with your doctor any other medications you take before you are given pentazocine.

This medication can be extremely dangerous if taken at the same time as alcohol is consumed.