Eli Lilly

(LLY) - Get Report

shares fell Friday after the company said it has added a bolded warning to the product label for Strattera, its treatment for attention deficit/hyperactivity disorder, or ADHD.

The company said the warning states the medication should be discontinued in patients with jaundice or laboratory evidence of liver injury. Lilly said the label change is the result of two reported cases of severe liver injury out of the more than 2 million patients who have taken the medication since approval. Both patients have recovered with normal liver function after discontinuing the medication.

Lilly said it had "worked closely" with the Food and Drug Administration "to determine the best course of action, and as a result, are taking a number of measures to notify health care professionals and ultimately patients."

The drugmaker stressed that the 6,000 patients taking Strattera in clinical trials did not show liver injury. "Real-world reports indicate that Strattera can cause severe liver injury in rare cases," the company said.

ADHD affects 3% to 7% of school-age children and manifests itself in levels of attention, concentration, activity, distractibility and impulsivity that are inappropriate for the age group, according to the company's news release.

Shares fell $2.04, or 3.5%, to $55.36.