Skip to Content

Pentazocine Side Effects

Medically reviewed by Last updated on July 24, 2020.

For the Consumer

Applies to pentazocine: oral tablets


Special Alerts:

[Posted 07/23/2020]

TOPIC: Opioid Pain Relievers or Medicines to Treat Opioid Use Disorder: MedWatch Safety Alert - FDA Recommends Health Care Professionals Discuss Naloxone with All Patients when Prescribing

AUDIENCE: Patient, Health Professional, Pharmacy

ISSUE: FDA is requiring drug manufacturers for all opioid pain relievers and medicines to treat opioid use disorder (OUD) to add new recommendations about naloxone to the prescribing information. This will help ensure that health care professionals discuss the availability of naloxone and assess each patient's need for a naloxone prescription when opioid pain relievers or medicines to treat OUD are being prescribed or renewed. The patient Medication Guides, available at: [Web], will also be updated.

BACKGROUND: Opioid pain relievers are medicines that can help manage pain when other treatments and medicines are not able to provide enough pain relief. Certain opioids are also used to treat OUD. Opioids have serious risks, including misuse and abuse, addiction, overdose, and death. Naloxone can help reverse opioid overdose to prevent death.

The misuse and abuse of illicit and prescription opioids and the risks of addiction, overdose, and death are a public health crisis in the United States. As a result, FDA is committed to encouraging health care professionals to raise awareness of the availability of naloxone when they are prescribing and dispensing opioid pain relievers or medicines to treat OUD. FDA held discussions about naloxone availability with the Anesthetic and Analgesic Drug Products and the Drug Safety and Risk Management Advisory Committees, available at: [Web], which recommended that all patients being prescribed opioids for use in the outpatient setting would benefit from a conversation with their health care professional about the availability of naloxone.



  • Talk to your health care professionals about the benefits of naloxone and how to obtain it.

  • Recognize the signs and symptoms of a possible opioid overdose. These include slowed, shallow, or difficult breathing, severe sleepiness, or not being able to respond or wake up. If you know or think someone is overdosing, give the person naloxone if you have access to it, and always call 911 or go to an emergency room right away. Naloxone is a temporary treatment, so repeat doses may be required. Even if you give naloxone, you still need to get emergency medical help right away.

  • If you have naloxone, make sure to tell your caregivers, household members, and other close contacts that you have it, where it is stored, and how to properly use it in the event of an overdose. When using opioid medicines away from home, carry naloxone with you and let those you are with know you have it, where it is, and how to use it. Read the Patient Information leaflet or other educational material and Instructions for Use that comes with your naloxone because it explains important information, including how to use the medicine.

Health Care Professionals:

  • Discuss the availability of naloxone with all patients when prescribing or renewing an opioid analgesic or medicine to treat OUD.

  • Consider prescribing naloxone to patients prescribed medicines to treat OUD and patients prescribed opioid analgesics who are at increased risk of opioid overdose.

  • Consider prescribing naloxone when a patient has household members, including children, or other close contacts at risk for accidental ingestion or opioid overdose.

  • Additionally, even if the patients are not receiving a prescription for an opioid analgesic or medicine to treat OUD, consider prescribing naloxone to them if they are at increased risk of opioid overdose.

  • Educate patients and caregivers on how to recognize respiratory depression and how to administer naloxone. Inform them about their options for obtaining naloxone as permitted by their individual state, available at: [Web], dispensing and prescribing requirements or guidelines for naloxone. Emphasize the importance of calling 911 or getting emergency medical help right away, even if naloxone is administered.

For more information visit the FDA website at: [Web] and [Web].


FDA approved a REMS for pentazocine to ensure that the benefits outweigh the risk. The REMS may apply to one or more preparations of pentazocine and consists of the following: medication guide and elements to assure safe use. See the FDA REMS page ([Web]).

Side effects include:

Dizziness, lightheadedness, euphoria, sedation, nausea.

For Healthcare Professionals

Applies to pentazocine: injectable solution


The most commonly occurring adverse reactions have included nausea, dizziness or lightheadedness, vomiting, and euphoria.


Postmarketing reports: Soft tissue induration, nodules and cutaneous depressions at injection sites; ulceration (sloughing), severe sclerosis of the skin and subcutaneous tissues and, rarely, underlying muscle; diaphoresis, sting on injection, flushed skin including plethora, dermatitis including pruritus[Ref]


Postmarketing reports: Anaphylaxis, facial edema, toxic epidermal necrolysis[Ref]

Nervous system

Serotonin syndrome has been reported during concomitant use of opioids with serotonergic drugs.[Ref]

Postmarketing reports: Dizziness, lightheadedness, sedation, headache, weakness, flushing, syncope, tremor, paresthesia


Postmarketing reports: Serotonin syndrome[Ref]


Postmarketing reports: Depression, euphoria, confusion, disorientation, disturbed dreams, insomnia, irritability, excitement, hallucinations[Ref]


Postmarketing reports: Respiratory depression, dyspnea, transient apnea (in infants whose mothers received this drug during labor)[Ref]


Postmarketing reports: Circulatory depression, shock, hypertension, tachycardia, syncope[Ref]


Postmarketing reports: Nausea, vomiting, constipation, dry mouth, taste alteration, diarrhea and cramps[Ref]


Depression of the white blood cell count is usually reversible.[Ref]

Postmarketing reports: Depression of the white blood cell count (especially granulocytes), moderate transient eosinophilia[Ref]


Postmarketing reports: Tinnitus, chills[Ref]


Postmarketing reports: Visual blurring and focusing difficulty, blurred vision, diplopia, miosis, nystagmus[Ref]


Postmarketing reports: Urinary retention, alteration in rate or strength of labor contractions[Ref]



Postmarketing reports: Adrenal insufficiency, Androgen deficiency

Cases of adrenal insufficiency have been reported with opioid use, generally use greater than 1 month. Cases of androgen deficiency have been reported with chronic opioid use.


1. "Product Information. Talwin NX (pentazocine)." Sanofi Winthrop Pharmaceuticals, New York, NY.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.