Tencon Side Effects

Generic name: acetaminophen / butalbital

Note: This document contains side effect information about acetaminophen / butalbital. Some of the dosage forms listed on this page may not apply to the brand name Tencon.

Some side effects of Tencon may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to acetaminophen / butalbital: oral capsule, oral tablet

Get emergency medical help if you have any of these signs of an allergic reaction while taking acetaminophen / butalbital: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

• fast or pounding heart rate, feeling short of breath;

• feeling like you might pass out;

• confusion, depression;

• feeling restless, excited, or agitated;

• seizure (convulsions); or

• nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Less serious side effects include:

• headache, dizziness, drowsiness, shaky feeling;

• drunk feeling;

• vomiting, constipation;

• heartburn, trouble swallowing;

• numbness or tingly feeling;

• dry mouth;

• sweating or urinating more than usual;

• leg pain, tired muscles;

• stuffy nose, ear pain, ringing in your ears; or

• mild itching.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to acetaminophen / butalbital: oral capsule, oral tablet

Nervous system

Nervous system side effects including drowsiness, lightheadedness, dizziness, sedation, and an intoxicated feeling have been reported frequently from the use of butalbital. Headache and seizures have been reported infrequently. Mental confusion, excitement, or depression have also been reported due to either intolerance (primarily in elderly or debilitated patients) or due to an overdose of butalbital.

Hepatic

Hepatic side effects including severe and sometimes fatal dose dependent hepatitis has been reported with the use of acetaminophen in alcoholic patients. Hepatotoxicity has been increased during fasting. Several cases of hepatotoxicity from chronic acetaminophen therapy at therapeutic doses have also been reported despite a lack of risk factors for toxicity.

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. However, 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.

Gastrointestinal

Gastrointestinal side effects including nausea, vomiting, and abdominal pain have been reported frequently with the use of butalbital. Gastrointestinal side effects are rare with acetaminophen use, except in alcoholics and after overdose. Cases of acute pancreatitis have been reported rarely with the use of acetaminophen.

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.

Renal

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

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 as well.

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 pills per day.

Hypersensitivity

Hypersensitivity side effects including anaphylaxis and fixed drug eruptions have been reported rarely in association with acetaminophen use.

Hematologic

Hematologic side effects including rare cases of thrombocytopenia associated with acetaminophen have been reported. Acute thrombocytopenia has also been reported as having been caused by sensitivity to acetaminophen glucuronide, the major metabolite of acetaminophen. Methemoglobinemia with resulting cyanosis has also been observed in the setting of acute overdose.

Dermatologic

Dermatologic side effects including acetaminophen associated bullous erythema and purpura fulminans have been reported. Erythematous skin rashes associated with acetaminophen have been reported rarely.

Respiratory

Respiratory side effects including dyspnea have been reported frequently with the use of butalbital. A case of acetaminophen-induced eosinophilic pneumonia has been reported.

Cardiovascular

Cardiovascular side effects including several cases of hypotension have been reported following the administration of acetaminophen.

Two cases 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.

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