Pentazocine Side Effects

Medically reviewed by Drugs.com. Last updated on Mar 14, 2025.

Applies to pentazocine: oral tablets.

Important warnings This medicine can cause some serious health issues

REMS:

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]).

• FDA drug safety communication (4/13/2023):⁵⁰⁰ As part of its ongoing efforts to address the nation’s opioid crisis, FDA is requiring several updates to the prescribing information of opioid pain medicines.

  The changes are being made to provide additional guidance for safe use of these drugs while also recognizing the important benefits when used appropriately.

  The changes apply to both immediate-release (IR) and extended-release/long-acting preparations (ER/LA).

• Updates to the IR opioids state that these drugs should not be used for an extended period unless the pain remains severe enough to require an opioid pain medicine and alternative treatment options are insufficient, and that many acute pain conditions treated in the outpatient setting require no more than a few days of an opioid pain medicine.

• Updates to the ER/LA opioids recommend that these drugs be reserved for severe and persistent pain requiring an extended period of treatment with a daily opioid pain medicine and for which alternative treatment options are inadequate.

• A new warning is being added about opioid-induced hyperalgesia (OIH) for both IR and ER/LA opioid pain medicines.

  This includes information describing the symptoms that differentiate OIH from opioid tolerance and withdrawal.

• Information in the boxed warning for all IR and ER/LA opioid pain medicines will be updated and reordered to elevate the importance of warnings concerning life-threatening respiratory depression, and risks associated with using opioid pain medicines in conjunction with benzodiazepines or other medicines that depress the central nervous system (CNS).

• Other changes will also be required in various other sections of the prescribing information to educate clinicians, patients, and caregivers about the risks of these drugs.

Side effects include:

Dizziness, lightheadedness, euphoria, sedation, nausea.

For healthcare professionals

Applies to pentazocine: injectable solution.

General adverse events

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

Dermatologic

• 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]

Hypersensitivity

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

Nervous system

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

Opioids:

• Postmarketing reports: Serotonin syndrome^[Ref]

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

Psychiatric

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

Respiratory

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

Cardiovascular

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

Gastrointestinal

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

Hematologic

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

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

Other

• Postmarketing reports: Tinnitus, chills^[Ref]

Ocular

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

Genitourinary

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

Endocrine

Opioids:

• 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.

Further information

Pentazocine side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer