Naloxone / Pentazocine Side Effects

Medically reviewed by Drugs.com. Last updated on Dec 22, 2024.

Applies to naloxone / pentazocine: oral tablet.

Precautions

It is very important that your doctor check your or your child's progress while using this medicine, especially within the first 24 to 72 hours of treatment. This will allow your doctor to see if the medicine is working properly and to decide if you or your child should continue to use it. Blood and urine tests may be needed to check for unwanted effects.

Symptoms of an overdose include: extreme dizziness or weakness, slow heartbeat or breathing, seizures, trouble breathing, and cold, clammy skin. Call your doctor right away if you notice these symptoms.

Do not use this medicine if you are using or have used an MAO inhibitor (MAOI) such as isocarboxazid (Marplan®), linezolid (Zyvox®), phenelzine (Nardil®), selegiline (Eldepryl®), tranylcypromine Parnate®) within the past 14 days.

This medicine will add to the effects of alcohol and other central nervous system (CNS) depressants (medicines that can make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for allergies or colds, sedatives, tranquilizers, or sleeping medicine, other prescription pain medicine or narcotics, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics. Check with your doctor before you or your child take any of the medicines listed above while you are using this medicine.

This medicine may be habit-forming. If you or your child feel that the medicine is not working as well, do not use more than your prescribed dose. Call your doctor for instructions.

Dizziness, lightheadedness, or fainting may occur when you get up suddenly from a lying or sitting position. These symptoms are more likely to occur when you begin using this medicine, or when the dose is increased. Getting up slowly may help lessen this problem. Also, lying down for a while may relieve dizziness or lightheadedness.

This medicine may make you dizzy, drowsy, or lightheaded. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

Using narcotics for a long time can cause severe constipation. To prevent this, your doctor may direct you or your child to take laxatives, drink lots of fluids, or increase the amount of fiber in your diet. Be sure to follow the directions carefully, because continuing constipation can lead to more serious problems.

If you or your child have been using this medicine regularly for several weeks or longer, do not change your dose or suddenly stop using it without checking with your doctor. Your doctor may want you or your child to gradually reduce the amount you are using before stopping it completely. This may help prevent worsening of your condition and reduce the possibility of withdrawal symptoms, such as abdominal or stomach cramps, anxiety, fever, nausea, runny nose, sweating, tremors, or trouble with sleeping.

This medicine may cause serious allergic reactions, including anaphylaxis, which can be life-threatening and require immediate medical attention. Call your doctor right away if you have a rash, itching, hoarseness, trouble breathing or swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.

Check with your doctor right away if you have anxiety, restlessness, a fast heartbeat, fever, sweating, muscle spasms, twitching, nausea, vomiting, diarrhea, or see or hear things that are not there. These may be symptoms of a serious condition called serotonin syndrome. Your risk may be higher if you also take certain other medicines that affect the serotonin levels in your body.

Using this medicine while you are pregnant may cause serious unwanted effects, including neonatal opioid withdrawal syndrome in your newborn baby. Tell your doctor right away if you think you are pregnant or if you plan to become pregnant while using this medicine.

Using too much of this medicine may cause infertility (unable to have children). Talk with your doctor before using this medicine if you plan to have children.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects

Along with its needed effects, naloxone / pentazocine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking naloxone / pentazocine:

Get emergency help immediately if any of the following symptoms of overdose occur while taking naloxone / pentazocine:

Symptoms of overdose

• chest pain
• choking
• cold and clammy skin
• constricted, pinpoint, or small pupils (black part of the eye)
• coughing that sometimes produces a pink frothy sputum
• decreased awareness or responsiveness
• difficult, fast, or noisy breathing
• extremely shallow or slow breathing
• increased sweating
• loss of consciousness
• no muscle tone or movement
• pale skin
• seeing, hearing, or feeling things that are not there
• severe sleepiness or unusual drowsiness
• seizures (convulsions)
• slow heartbeat
• swelling in the legs and ankles

Other side effects

Some side effects of naloxone / pentazocine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

For healthcare professionals

Applies to naloxone / pentazocine: oral tablet.

General adverse events

The most commonly occurring adverse reactions have included nausea, dizziness, lightheadedness, vomiting, and euphoria.^[Ref]

Respiratory

• Postmarketing reports: Respiratory depression

Psychiatric

• Postmarketing reports: Hallucinations (usually visual), confusion, disorientation, depression, euphoria, disturbed dreams, insomnia, irritability, excitement, irritability

Hypersensitivity

• Postmarketing reports: Anaphylaxis, facial edema, rash

Cardiovascular

• Postmarketing reports: Hypertension, hypotension, circulatory depression, tachycardia, syncope

A 45-year-old male narcotic addict and alcoholic with hepatitis and undiscovered cardiomyopathy was given 0.8 mg of naloxone intravenously over a 2 minute period and developed ventricular fibrillation. The patient required naloxone once more for this episode and again developed ventricular fibrillation. A second opioid overdose in the same patient was treated with an initial dose of 0.4 mg intravenously, followed by 0.4 mg intravenously, then intramuscularly. Each time the patient developed ventricular fibrillation responsive to cardioversion and/or lidocaine.

Severe hypertension (mean arterial pressure rising from a baseline of 107 mmHg to 147 mmHg in about 2 to 3 hours) has been reported in an essential hypertension patient given an initial 8 mg dose of naloxone intravenously, followed by an infusion of 0.13 mg/min over the next 2.5 hours. When the naloxone was discontinued the blood pressure quickly returned to normal.

Mild hypotension and one case of moderate hypertension were observed in patients receiving a bolus dose of 4 mg/kg of naloxone followed by 2 mg/kg/hour for 24 hours. One study reported that the newborn infants of mothers who have received naloxone near term may experience tachycardia.

Gastrointestinal

• Postmarketing reports: Nausea, vomiting, constipation, diarrhea, anorexia, biliary tract spasms, dry mouth, abdominal distress

Dermatologic

• Postmarketing reports: Sweating, flushed skin, dermatitis, pruritus, rash, urticaria, serous skin reactions including erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis

Other

• Postmarketing reports: Tinnitus, chills

Withdrawal syndromes from the use of naloxone may be precipitated by as little as 0.05 to 0.2 mg intravenously in patients taking 24 mg per day of methadone.

Ocular

• Postmarketing reports: Visual blurring and focusing difficulty, blurred vision, diplopia, miosis, nystagmus

Genitourinary

• Postmarketing reports: Urinary retention, alteration in rate or strength of labor contractions

Hematologic

• Postmarketing reports: Depression of the white blood cell count (especially granulocytes), moderate transient eosinophilia, agranulocytosis

Depression of the white blood cell count is usually reversible.

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.

See also:

Further information

Naloxone/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.

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