Shares of the Dublin, Ohio company were tumbling 10.1% to $54.66 at last check.
Cardinal Health reported net income of $119 million, or 40 cents a share, a third of the $350 million, or $1.19 a share, in the year-earlier quarter.
Excluding special items, the latest adjusted earnings per share came to $1.53, missing FactSet's analyst consensus of $1.55 a share.
Revenue totaled $39.3 billion, up from $39.2 billion but short of FactSet's call for $40.1 billion.
The company said a decline in its pharmaceutical segment stemmed primarily from COVID-19-related volume declines in the company's generics program.
The company reduced its fiscal 2021 adjusted earnings guidance range to $5.90 to $6.05 a share, from earlier guidance of $5.85 to $6.10.
"With our resilient business model and strong fundamentals, we are navigating the effects of the pandemic and finding opportunities to adapt, innovate and invest," Chief Executive Mike Kaufmann said in a statement.
Cowen analyst Charles Rhyee said in a research note that a higher-than-expected tax rate drove the earnings miss. He rates the stock market perform with a $59 price target.
Evercore ISI analyst Elizabeth Anderson, who has an in-line rating on the stock with a target of $62, cited lighter-than-expected revenue for its pharmaceuticals business paired with a miss for its medical arm, according to Bloomberg.
Baird analyst Eric Coldwell, who has an outperform rating and a $66 price target, said “results and outlook won’t suffice” with initial investor feedback on the earnings coming in negative.
In March, Cardinal Health said it would sell Cordis, its medical-device business, to private-equity firm Hellman & Friedman for about $1 billion.