Acetaminophen/Pentazocine Side Effects

Please note - some side effects for Acetaminophen/Pentazocine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA at http://www.fda.gov/medwatch/ or 1-800-FDA-1088 (1-800-332-1088).

Side Effects of Acetaminophen/Pentazocine - for the Consumer

Acetaminophen/Pentazocine

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome when using Acetaminophen/Pentazocine:

Constipation; dizziness; drowsiness; exaggerated sense of well-being; headache; lightheadedness; nausea; sweating; vomiting.

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blistered, red, or swollen skin; confusion; disorientation; fast heartbeat; fainting; hallucinations; mental or mood changes; seizures; severe dizziness; severe stomach pain; tremor; trouble sleeping; trouble urinating; vision problems or blurred vision; weakness.

Side Effects by Body System

Cardiovascular

Two cases of hypotension have been reported following the administration of acetaminophen. Both patients experienced significant decreases in blood pressure. One of the two patients required pressor agents to maintain adequate mean arterial pressures. Neither episode was associated with symptoms of anaphylaxis. Neither patient was rechallenged after resolution of the initial episode.

Cardiovascular side effects have included at least two cases of hypotension which have been reported following the administration of acetaminophen. Cardiovascular side effects with pentazocine have included hypotension and tachycardia.

Dermatologic

Dermatologic side effects including general erythematous skin rashes associated with acetaminophen have been reported, but are rare. Cases of bullous erythema and purpura fulminans associated with acetaminophen have been reported. Dermatologic side effects with pentazocine have included serious skin reactions, including erythema multiforme, Stevens-Johnson Syndrome, and toxic epidermal necrolysis.

Gastrointestinal

Gastrointestinal side effects with acetaminophen are rare except in alcoholics and after overdose. However, nausea, vomiting, and diarrhea have been reported with ordinary doses of acetaminophen. Cases of acute pancreatitis have been reported rarely. Gastrointestinal side effects with pentazocine have included nausea, vomiting, constipation, abdominal distress, anorexia, and diarrhea.

One study has suggested that acetaminophen may precipitate acute biliary pain and cholestasis. The mechanism of this effect may be related to inhibition of prostaglandin and alterations in the regulation of the sphincter of Oddi.

General

In general, acetaminophen is well tolerated when administered in therapeutic doses.

Hematologic

Hematologic side effects have included rare cases of thrombocytopenia associated with acetaminophen. Methemoglobinemia with resulting cyanosis has also been observed in the setting of acute overdose. Hematologic side effects with pentazocine have included depression of white blood cells (especially granulocytes), which is usually reversible, and moderate transient eosinophilia.

Hepatic

Hepatic side effects have included hepatic dysfunction which may occur after overdose. In this setting, severe and sometimes fatal dose-dependent hepatitis has been reported. Several cases of hepatotoxicity from chronic acetaminophen therapy at therapeutic doses have also been reported despite a lack of risk factors for toxicity.

Hepatotoxicity may be increased by thyroid drugs, zidovudine, fasting, or alcohol use.

Alcoholic patients may develop hepatotoxicity after even modest doses of acetaminophen. In healthy patients, approximately 15 grams of acetaminophen is necessary to deplete liver glutathione stores by 70% in a 70 kg person. Hepatotoxicity has been reported following smaller doses. Glutathione concentrations may be repleted by the antidote N-acetylcysteine. One case report has suggested that hypothermia may also be beneficial in decreasing liver damage during overdose.

In a recent retrospective study of 306 patients admitted for acetaminophen overdose, 6.9% had severe liver injury but all recovered. None of the 306 patients died.

A 19-year-old female developed hepatotoxicity, reactive plasmacytosis and agranulocytosis followed by a leukemoid reaction after acute acetaminophen toxicity.

Hypersensitivity

Hypersensitivity side effects with acetaminophen have included rare reports of anaphylaxis and fixed drug eruptions. A few cases of acetaminophen hypersensitivity (as manifested by skin rashes, thrombocytopenic purpura, hemolytic anemia, and agranulocytosis) have been reported. Hypersensitivity side effects with pentazocine have included rash, urticaria, edema of the face, and in at least one case, an apparent anaphylactic reaction.

Renal

Acetaminophen related acute tubular necrosis usually occurs in conjunction with liver failure, but has been observed as an isolated finding in rare cases. A possible increase in the risk of renal cell carcinoma has been associated with chronic acetaminophen use.

A recent case-control study of patients with end-stage renal disease suggested that long term consumption of acetaminophen may significantly increase the risk of end-stage renal disease particularly in patients taking more than two tablets per day.

Renal side effects of acetaminophen are rare and have included acute tubular necrosis and interstitial nephritis. Additional adverse renal effects are most often observed after overdose, after chronic abuse (often with multiple analgesics), or in association with acetaminophen-related hepatotoxicity.

Respiratory

Respiratory side effects have included a case of eosinophilic pneumonia which has been associated with acetaminophen. Respiratory side effects with pentazocine have included respiratory depression.

Nervous system

Nervous system side effects with pentazocine have included dizziness, lightheadedness, sedation, headache, confusion, disorientation, weakness, insomnia, syncope, focusing difficulty, depression, tremor, irritability, excitement, tinnitus, and paresthesia.

Psychiatric

Psychiatric side effects have included hallucinations, euphoria, and disturbed dreams.

Other

Other side effects with pentazocine have included sweating, flushing, and chills.

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