With extreme haste and with tight security restrictions, Mallinckrodt developed a novel technique from theoretical concept, to experiment, to full production.

[16] Viewed as an attractive takeover target in the era of leveraged buyouts, Mallinckrodt was bought by Avon Products in 1982, and largely kept intact as a business entity.

[19] As of 1988[update], Mallinckrodt is the only company in the U.S. that is allowed to receive cocaine, which is sold as a prescription drug for use in hospitals as a local anesthetic by eye and ear, nose and throat (ENT) doctors.

[22] In 2018, Mallinckrodt partnered with the Washington University School of Medicine with funding of up to $10 million over five years to support research projects that show promise in developing new drugs for treating rare diseases.

In 2015, Mallinckrodt was one of several U.S. tax inversions that The Wall Street Journal reported to be using a lower tax-platform to acquire further U.S. pharmaceutical firms, such as the $5.6 billion acquisition of Questor in 2014.

[26] In December 2015, The Irish Times reported the CEO as saying that "It'd have to be a pretty dramatic change to the US tax code" for Mallinckrodt to return to the U.S., and that "We're already foreign domiciled, so we may as well take full advantage of it".

Acthar Gel,[a] reported: "How the price of this drug rose so far, so fast is a story for these troubled times in American health care—a tale of aggressive marketing, questionable medicine and, not least, out-of-control costs".

[31] In January 2017, the Financial Times reported that Mallinckrodt had made a settlement of $100 million with the U.S. Federal Trade Commission (FTC) in relation to antitrust probes on Acthar and quoted the FTC as saying: "Questcor [Mallinckrodt's subsidiary] took advantage of its monopoly to repeatedly raise the price of Acthar, from $40 per vial in 2001 to more than $34,000 per vial today – an 85,000 percent increase".

[32] The city of Rockford, Illinois, is now suing Mallinckrodt and pharmacy benefit management company Express Scripts for their failure to reduce Acthar's price.

[29][37] A whistleblower filed a qui tam action in 2018 alleging that Mallinckrodt failed to pay the correct Medicaid rebates for Acthar in violation of the federal and state False Claims Acts.

[42] A US Drug Enforcement Administration (DEA) database tracking every opioid pill sold in the United States from 2006 through 2012 was made public in 2019.

The database "attributed the vast majority of the 76 billion opioid pills produced and shipped from 2006 through 2012 to three companies", one of which was SpecGx, a subsidiary of Mallinckrodt.

"[6] In February 2020, the company struck a $1.6 billion deal with Florida and dozens of other states to settle lawsuits over its role in the US opioid crisis.

[43] In October 2020, Mallinckrodt filed for Chapter 11 bankruptcy protection while facing more than $1 billion in costs from lawsuits over its role in fueling the opioid crisis.

[44] On June 2, 2023, Mallinckrodt announced that they would be considering a second Chapter 11 bankruptcy protection filing after lenders of the company raised concerns over an upcoming $200 million payment related to opioid-related litigation that was due in the coming weeks.

[48] On July 11, 2023, Mallinckrodt was sued for allegedly misleading investors for misrepresenting its financial strength before missing payments to opioid victims and bond holders.

If this plan turns out successful, victims of the opioid payment could lose up to a maximum of $1 billion, and the money could end up going to funds and investors instead.

The remaining business of specialty branded products will be renamed and led by current Chief Executive Officer, Mark Trudeau.