Side effects: Most common: drowsiness, dizziness, lightheadedness, shortness of breath, abdominal pain, and intoxicated feeling. Less frequent headache, shaky feeling, numbness seizure, tachycardia, leg pain, muscle fatigue, irritability, tremor, nephrotoxicity, hyperglycemia, diuresis, fever, earache, nasal congestion, tinnitus, and allergic reactions, and GI upset (nausea, vomiting, and flatulence). Several cases of dermatological reactions have been reported.

Side effects if contains acetaminophen: rash, thrombocytopenia, and agranulocytosis.

Side effects if contains aspirin: occult blood loss, anemias, peptic ulcer, prolonged bleeding time, and acute airway obstruction.

Side effects if contains codeine: constipation and pruritus.

Drug abuse and dependence:

Butalbital may be habit forming. Tolerance, physiological dependence and physical dependence may occur especially with prolonged use of high doses of barbiturates. The average daily dose for barbiturate addiction is usually about 1500 mg. As tolerance to barbiturates develops, the amount needed to maintain the same level of intoxication increases; tolerance to a fatal dose does not increase more than two fold. The lethal dose of barbiturates is far less is alcohol is also ingested. Withdrawal symptoms (convulsions and delirium) may occur with in 16 hours and last up to 5 days after abrupt cessation of these drugs. Intensity of withdrawal symptoms gradually declines over approximately 15 days. Treatment of barbiturate dependence requires gradual withdrawal of the drug.

Overdose:

Toxicity from barbiturate: drowsiness, confusion, coma, respiratory depression, hypotension, and hypovolemic shock.

Toxicity from acetaminophen: potentially fatal hepatic necrosis, renal tubular necroses, hypoglycemic coma and thrombocytopenia. Early symptoms; nausea, vomiting, diaphoresis and general malaise. Clinical and laboratory evidence of hepatic toxicity may not be apparent until 48-72 hours post ingestion. In adults hepatic toxicity has rarely been reported with acute overdose of less than 10 grams or fatalities with less than 15 grams.

Toxicity from caffeine: insomnia, restlessness, tremor, delirium, tachycardia, and extrasystoles.

Toxicity from codeine: pinpoint pupils, respiratory depression, loss of consciousness, and convulsions.

Toxicity from aspirin: hyperpnea, acid-base disturbances (metabolic acidosis, vomiting, abdominal pain, tinnitus, hyperthermia, hypoprothrombinemia, restlessness, delirium and convulsion.

Toxic and lethal doses:

• Butlabital: Toxic dose 1.0gm. (adult) Lethal doses 2 to 5 gm.
• Aspirin: Toxic blood level greater than 30 mg/100ml. Lethal dose 10-30g. (adult)
• Caffeine: Toxic dose greater than 1.0 gm. Lethal dose unknown.
• Codeine: Toxic dose 240 mg. Lethal dose 0.5 to 1.0 gm (adult).
• Acetaminophen: Toxic dose 10.0gm