Alanine aminotransferase (ALT) elevations are common in a significant percentage of individuals who initiate acetaminophen use at 4 grams per day, the maximum recommended dosage. In a 14-day randomized study, 145 healthy adults were given the maximum daily dosage of acetaminophen (either alone or with an opioid) or placebo. Between 31% and 44% of all patients receiving acetaminophen had ALT elevations three times higher than normal. There were no such elevations in the placebo group. It's advised that acetaminophen dosage be taken into account when identifying ALT elevation.

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