Exhibit 99.1

Unaudited pro forma combined financial information

The following unaudited pro forma combined financial information is presented to illustrate the estimated effects of (i) the acquisition of Allergan, Inc. (“Legacy Allergan”) by Actavis plc, which closed on March 17, 2015 (the “Legacy Allergan Acquisition”), (ii) the acquisition of Forest Laboratories, Inc. (“Forest”) by Actavis plc which closed on July 1, 2014, (the “Forest Acquisition”), (iii) the acquisition of Aptalis Holdings Inc. (“Aptalis”) by Forest, which closed on January 31, 2014 (the “Aptalis Acquisition”), and (iv) the related financings to fund the acquisitions referenced in (i), (ii) and (iii) and based on the historical financial position and results of operations of Allergan. The following unaudited pro forma combined financial information does not, however, illustrate the effect of the Company’s pending acquisition of KYTHERA Biopharmaceuticals, Inc.

References throughout to “we,” “our,” “us,” “Allergan,” or the “Company” refer to Allergan plc.

The fiscal years of the Company and Legacy Allergan ended on December 31. The fiscal years of Forest and Aptalis ended on March 31 and September 30, respectively. The following unaudited pro forma combined statement of operations for the three months ended March 31, 2015 was prepared based on (i) the historical consolidated statement of operations of the Company for the three months ended March 31, 2015 and (ii) the historical consolidated statement of operations of Legacy Allergan for the period of January 1, 2015 through March 16, 2015. The following unaudited pro forma combined statement of operations for the year ended December 31, 2014 was prepared based on (i) the historical consolidated statement of operations of the Company for the year ended December 31, 2014, (ii) the historical consolidated statement of operations of Legacy Allergan for the year ended December 31, 2014, (iii) the historical consolidated statement of operations of Forest for the six months ended June 30, 2014, which was derived by subtracting the consolidated statement of operations for the nine months ended December 31, 2013 and adding the consolidated statement of operations for the fiscal year ended March 31, 2014 from and to the consolidated statement of operations for the three months ended June 30, 2014, and (iv) the historical consolidated statement of operations of Aptalis for the one month ended January 31, 2014.

The Legacy Allergan Acquisition, the Forest Acquisition and the Aptalis Acquisition have been accounted for as business combinations using the acquisition method of accounting under the provisions of Accounting Standards Codification (“ASC”) 805, “Business Combinations,” (“ASC 805”). The unaudited pro forma combined financial information set forth below primarily give effect to the following:

The pro forma adjustments are based upon available information and certain assumptions, described in the accompanying notes to the unaudited pro forma combined financial information that Company management believes are reasonable under the circumstances. Actual results may differ materially from the assumptions within the accompanying unaudited pro forma combined financial information. Under ASC 805, assets acquired and liabilities assumed are recorded at fair value. The fair value of identifiable tangible and intangible assets acquired and liabilities assumed from the acquisitions are based on an estimate of fair value as of the acquisition dates. Any excess of the purchase price over the fair value of identified assets acquired and liabilities assumed is recognized as goodwill. Significant judgment is required in determining the estimated fair values of in-process research and development (“IPR&D”), identifiable intangible assets and certain other assets and liabilities. Such a valuation requires estimates and assumptions including, but not limited to, determining the timing and estimated costs to complete each in-process project, projecting the timing of regulatory approvals, estimating future cash flows and direct costs in addition to developing the appropriate discount rates and current market profit margins. Company management believes the fair values recognized for the assets acquired and the liabilities assumed, based in part on preliminary valuations, are based on reasonable estimates and assumptions.

The unaudited pro forma combined statements of operations for the three months ended March 31, 2015 and the fiscal year ended December 31, 2014 assume all of the transactions were completed on January 1, 2014. The unaudited pro forma combined financial information has been prepared by Company management in accordance with SEC Regulation S-X Article 11 for illustrative purposes only and is not necessarily indicative of the combined results of operations that would have been realized had the transactions been completed as of the date indicated, nor is it meant to be indicative of any anticipated combined future results of operations that the Company will experience. In addition, the accompanying unaudited pro forma combined statements of operations do not include any pro forma adjustments to reflect expected cost savings which may be achievable or restructuring actions or the impact of any non-recurring activity and one-time transaction related costs.

Certain financial information of Legacy Allergan, Forest and Aptalis, as presented in their respective consolidated financial statements, has been reclassified to conform to the historical presentation in Allergan’s consolidated financial statements for purposes of preparation of the unaudited pro forma combined financial information.

Allergan plc

Unaudited pro forma combined statement of operations

For the three months ended March 31, 2015

See the accompanying notes to the unaudited pro forma combined financial information, which are an integral part of these pro forma financial statements.

Allergan plc

Unaudited pro forma combined statement of operations

For the year ended December 31, 2014

See the accompanying notes to the unaudited pro forma combined financial information, which are an integral part of these pro forma financial statements.

1. Description of transactions

The Legacy Allergan Acquisition:    On March 17, 2015, the Company acquired Legacy Allergan for approximately $77.0 billion including outstanding indebtedness assumed of $2.2 billion, cash consideration of $40.1 billion and equity consideration of $34.7 billion, which included the assumption of outstanding Legacy Allergan equity awards (the “Legacy Allergan Acquisition”). Under the terms of the merger agreement for the Legacy Allergan Acquisition, Legacy Allergan shareholders received 111.2 million of the Company’s ordinary shares, 7.0 million of the Company’s non-qualified stock options and 0.5 million of the Company’s share units.

The Company’s historical consolidated statement of operations for the three months ended March 31, 2015 includes results of operations of Legacy Allergan since March 17, 2015.

Forest Acquisition:    On July 1, 2014, the Company acquired Forest for $30.9 billion, including outstanding indebtedness assumed of $3.3 billion, equity consideration of $20.6 billion, which included the assumption of outstanding Forest equity awards, and cash consideration of $7.1 billion (the “Forest Acquisition”). Under the terms of the Forest Acquisition, Forest stockholders and holders of Forest equity awards received 89.8 million of the Company’s ordinary shares, 6.1 million of the Company’s non-qualified stock options and 1.1 million of the Company’s share units. Included in the consideration is the portion of outstanding equity awards deemed to have been earned as of July 1, 2014 of $568.1 million (amount deemed not to have been earned as of July 1, 2014 was $570.4 million).

The Company’s historical consolidated statement of operations includes results of operations of Forest since July 1, 2014.

Aptalis Acquisition:    On January 31, 2014, Forest acquired Aptalis in a series of merger transactions for an aggregate purchase price equal to the total enterprise value of Aptalis, plus the aggregate exercise price applicable to Aptalis’ outstanding options and other equity awards, plus the amount of closing date cash, minus Aptalis’ existing indebtedness, minus certain selling stockholders’ expenses.

2. Basis of presentation

The historical consolidated financial information of the Company has been adjusted in the accompanying unaudited pro forma combined financial information to give effect to pro forma events that are (i) directly attributable to the transactions, (ii) factually supportable, and (iii) with respect to the unaudited pro forma combined statements of operations, are expected to have a continuing impact on the results of operations.

The unaudited pro forma combined financial information was prepared using the acquisition method of accounting in accordance with ASC 805, which requires, among other things, that assets acquired and liabilities assumed in a business combination be recognized at their fair values as of the acquisition date.

The acquisition method of accounting uses the fair value concepts defined in ASC 820, “Fair Value Measurement,” (referred to herein as “ASC 820”) as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” This is an exit price concept for the valuation of an asset or liability. Market participants are assumed to be buyers or sellers in the most advantageous market for the asset or liability. Fair value measurement for an asset assumes the highest and best use by these market participants. Fair value measurements can be highly subjective and it is possible the application of reasonable judgment could develop different assumptions resulting in a range of alternative estimates using the same facts and circumstances.

3. Historical Legacy Allergan

Financial information of Legacy Allergan in the unaudited pro forma combined statements of operations in the “Historical Legacy Allergan” column represents the historical consolidated statement of earnings of Legacy Allergan for the three months ended March 31, 2015 for the period when it was a stand-alone entity. Financial information of Legacy Allergan in the unaudited pro forma combined statements of operations in the “Historical Legacy Allergan (after conforming reclassifications)” column represents the historical consolidated statement of earnings of Legacy Allergan for the year ended December 31, 2014. Such financial information has been reclassified or classified to conform to the historical presentation in the Company’s consolidated financial statements as set forth below (in millions). Unless otherwise indicated, defined line items included in the footnotes have the meanings given to them in the historical financial statements of Legacy Allergan.

Reclassifications and classifications in the unaudited pro forma combined statement of operations for the year ended December 31, 2014

4. Historical Forest

Financial information presented in the “Historical Forest (after conforming reclassifications)” column in the unaudited pro forma combined statement of operations of Forest for the year ended December 31, 2014, is for the six months Forest was a stand-alone entity and was derived by subtracting the consolidated statement of operations for the nine months ended December 31, 2013 and adding the consolidated statement of operations for the fiscal year ended March 31, 2014 from and to the consolidated statement of operations for the three months ended June 30, 2014 as follows (in millions):

Financial information of Forest subsequent to July 1, 2014 is included in the results of the Company.

Financial information presented in the “Historical Forest (after conforming reclassifications)” column in the unaudited pro forma statement of operations for the year ended December 31, 2014, of

which six months represents the Forest results, has been reclassified or classified to conform to the historical presentation in the Company’s consolidated financial statements as set forth below (in millions). Unless otherwise indicated, defined line items included in the footnotes have the meanings given to them in the historical financial statements of Forest.

Reclassifications and classifications in the unaudited pro forma combined statement of operations for the year ended December 31, 2014

5. Unaudited pro forma combined statement of operations adjustments

Adjustments related to the Legacy Allergan Acquisition

Adjustments included in the “Legacy Allergan Acquisition Adjustments” column in the accompanying unaudited pro forma combined statements of operations are as follows:

Adjustments included in the “Legacy Allergan Financing Adjustments” column in the accompanying unaudited pro forma combined statement of operations are as follows:

Adjustments related to the Forest Acquisition

Adjustments included in the “Forest Acquisition Adjustments” column in the accompanying unaudited pro forma combined statement of operations for the year ended December 31, 2014 are as follows:

Adjustments included in the “Forest Financing Adjustments” column in the accompanying unaudited pro forma combined statement of operations are as follows:

For the term facilities associated with the Forest Acquisition of $2,000.0 million, a five year maturity was assumed. For the notes associated with the Forest Acquisition, various maturity dates were assumed ranging from 2017 to 2044. The assumed interest rate for these borrowings was 3.3% on a weighted average basis. Interest expense from the cash bridge loans associated with the Forest Acquisition was not reflected in the unaudited combined pro forma statement of operations as it will not have a continuing impact due to the short-term nature.

Adjustments related to the Aptalis Acquisition

Adjustments included in the “Aptalis Acquisition and Financing Adjustments” column in the accompanying unaudited pro forma combined statement of operations for the year ended December 31, 2014 is as follows:

6. Earnings per share

The unaudited pro forma combined basic and diluted earnings per share calculations are based on Allergan plc’s consolidated basic and diluted weighted average number of shares. The pro forma weighted average number of shares outstanding reflects the following adjustments assumed to occur on January 1, 2014: