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Exhibit 21.1

SUBSIDIARIES OF MALLINCKRODT PLC

The following is a list of subsidiaries of Mallinckrodt plc as of December 29, 2023.

Name of Subsidiary						Jurisdiction of Incorporation/Organization
Acthar IP Unlimited Company						Ireland
Cache Holdings Limited						Bermuda
Carnforth Limited						Bermuda
Dritte CORSA Verwaltungsgesellschaft GmbH						Germany
Ikaria Australia Pty Ltd						Australia
Ikaria Canada Inc.						Canada
IMC Exploration Company						Maryland
Infacare Pharmaceutical Corporation						Delaware
INO Therapeutics LLC						Delaware
Ludlow LLC						Massachusetts
MAK LLC						Delaware
Mallinckrodt APAP LLC						Delaware
Mallinckrodt ARD Finance LLC						Delaware
Mallinckrodt ARD Holdings Inc.						Delaware
Mallinckrodt ARD Holdings Limited						United Kingdom
Mallinckrodt ARD IP Unlimited Company						Ireland
Mallinckrodt ARD LLC						California
Mallinckrodt Brand Pharmaceuticals LLC						Delaware
Mallinckrodt Buckingham Unlimited Company						Ireland
Mallinckrodt Canada Cooperatie U.A.						Netherlands
Mallinckrodt Canada ULC						British Columbia
Mallinckrodt CB LLC						Delaware
Mallinckrodt Chemical Holdings (U.K.) Limited						United Kingdom
Mallinckrodt Chemical Limited						United Kingdom
Mallinckrodt Critical Care Finance LLC						Delaware
Mallinckrodt Enterprises Holdings LLC						California
Mallinckrodt Enterprises LLC						Delaware
Mallinckrodt Enterprises UK Limited						United Kingdom
Mallinckrodt Equinox Finance LLC						Delaware
Mallinckrodt Equinox Limited						United Kingdom
Mallinckrodt Finance Management Ireland Limited						Ireland
Mallinckrodt Group S.à r.l.						Luxembourg
Mallinckrodt Group S.à r.l., Luxembourg (LU) Schaffhausen Branch						Switzerland
Mallinckrodt Holdings GmbH						Switzerland
Mallinckrodt Hospital Products Inc.						Delaware
Mallinckrodt Hospital Products IP Unlimited Company						Ireland
Mallinckrodt International Finance SA						Luxembourg
Mallinckrodt International Holdings S. à r.l.						Luxembourg
Mallinckrodt IP Unlimited Company						Ireland
Mallinckrodt LLC						Delaware
Mallinckrodt Lux IP S.à r.l.						Luxembourg
Mallinckrodt Manufacturing LLC						Delaware
Mallinckrodt Medical Holdings (UK) Limited						United Kingdom
Mallinckrodt Medical Holdings (UK) Limited, Zweigniederlassung Deutschland (the German Branch)						Germany
Mallinckrodt Netherlands B.V.						Netherlands
Mallinckrodt Petten Holdings B.V.						Netherlands
Mallinckrodt Pharma IP Trading Unlimited Company						Ireland

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Mallinckrodt Pharma K.K.						Japan
Mallinckrodt Pharmaceuticals Ireland Limited						Ireland
Mallinckrodt Pharmaceuticals Limited						United Kingdom
Mallinckrodt Quincy S.à r.l.						Luxembourg
Mallinckrodt SAG Holdings GmbH						Switzerland
Mallinckrodt Securitization S.à r.l.						Luxembourg
Mallinckrodt UK Finance LLP						United Kingdom
Mallinckrodt UK Ltd						United Kingdom
Mallinckrodt US Holdings LLC						Delaware
Mallinckrodt US Pool LLC						Nevada
Mallinckrodt Veterinary, Inc.						Delaware
Mallinckrodt Windsor Ireland Finance Unlimited Company						Ireland
Mallinckrodt Windsor S.à r.l.						Luxembourg
MCCH LLC						Delaware
MEH, Inc.						Nevada
MHP Finance LLC						Delaware
MKG Medical UK Ltd						United Kingdom
MNK 2011 LLC						Delaware
Montjeu Limited						Ireland
MUSHI UK Holdings Limited						United Kingdom
OCERA Therapeutics LLC						Delaware
Petten Holdings Inc.						Delaware
Profibrix B.V.						Netherlands
Questcor International Limited						Ireland
Sonorant Therapeutics Limited						Ireland
SpecGx Holdings LLC						New York
SpecGx LLC						Delaware
ST 2020 LLC						Delaware
ST Operations LLC						Delaware
ST Shared Services LLC						Delaware
ST US AR Finance LLC						Delaware
ST US Holdings LLC						Nevada
ST US Pool LLC						Delaware
Stratatech Corporation						Delaware
Sucampo Finance Inc.						Delaware
Sucampo GmbH						Switzerland
Sucampo Holdings Inc.						Delaware
Sucampo International Holdings Limited						United Kingdom
Sucampo Pharma Americas LLC						Delaware
Sucampo Pharma LLC						Japan
Sucampo Pharmaceuticals LLC						Delaware
Therakos (Belgium) SPRL						Belgium
Therakos (Canada) Company						Nova Scotia
Therakos (France) SAS						France
Therakos (Italia) S.r.l.						Italy
Therakos (UK) Limited, Dutch Branch						Netherlands
Therakos (UK), Limited, Sucursal en Espana						Spain
Therakos (UK), Ltd						United Kingdom
Therakos (UK), Ltd (Prywatna Spólka Z Ograniczona Odpowiedzialnoscia) Oddzial W Polsce						Poland
Therakos (UK), Ltd, Sweden Filial						Sweden
Therakos EMEA Limited						Ireland
Therakos Europe Limited						Ireland
Therakos Germany GmbH						Germany
Therakos, Inc.						Florida

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Vtesse LLC						Delaware
WebsterGx Holdco LLC						New York