Exhibit 99.1

Lantheus Reports Fourth Quarter and Full Year 2023 Financial Results

Internet Posting of Information

Conference Call and Webcast

About Lantheus Holdings, Inc.

Non-GAAP Financial Measures

Safe Harbor for Forward-Looking and Cautionary Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, that are subject to risks and uncertainties and are made pursuant to the safe harbor provisions of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements may be identified by their use of terms such as “anticipate,” “believe,” “confident,” “continue,” “could,” “estimate,” “expect,” “guidance,” “intend,” “introduce,” “may,” “momentum,” “plan,” “potential,” “predict,” “progress,” “project,” “promising,” “prospect,” “should,” “target,” “will,” “would” and other similar terms. Such forward-looking statements include our guidance for fiscal year 2024 and are based upon current plans, estimates and expectations that are subject to risks and uncertainties that could cause actual results to materially differ from those described in the forward-looking statements. The inclusion of forward-looking statements should not be regarded as a representation that such plans, estimates and expectations will be achieved. Readers are cautioned not to place undue reliance on the forward-looking statements contained herein, which speak only as of the date hereof. The Company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future developments or otherwise, except as may be required by law. Risks and uncertainties that could cause our actual results to materially differ from those described in the forward-looking statements include: (i) continued market expansion and penetration for our established commercial products, particularly PYLARIFY and DEFINITY, in a competitive environment in which other imaging agents have been approved and are being commercialized, and our ability to clinically and commercially differentiate our products; (ii) our ability to have third parties manufacture our products and our ability to manufacture DEFINITY in our in-house manufacturing facility; (iii) the global availability of Molybdenum-99 (“Mo-99”) and other raw materials and key components; (iv) our strategies, future

prospects, and projected growth, including revenue related to our collaboration agreements with POINT Biopharma Global Inc. (“POINT”), including our ability to obtain FDA approval for PNT2002 and PNT2003; (v) our ability to satisfy our obligations under our existing clinical development partnerships using MK-6240 as a research tool and under the license agreement through which we have rights to MK-6240, and to further develop and commercialize it as an approved product; (vi) our ability to successfully execute on our agreements with Perspective Therapeutics, Inc. (“Perspective”), including finalizing the license agreements in the event we exercise our options to do so, and satisfying the closing conditions for the sale of the Somerset, NJ manufacturing facility and related assets, the value of our current and any future equity interest in Perspective, and Perspective’s ability to successfully develop its alpha-particle therapy and innovative platform technology; (vii) the efforts and timing for clinical development, regulatory approval and successful commercialization of our product candidates and new clinical applications and territories for our products, in each case, that we or our strategic partners may undertake; (viii) our ability to identify and acquire or in-license additional radiopharmaceutical therapeutic and diagnostic product opportunities in oncology and other strategic areas to grow our pipeline of products; and (ix) the risk and uncertainties discussed in our filings with the Securities and Exchange Commission (including those described in the Risk Factors section in our Annual Reports on Form 10-K and our Quarterly Reports on Form 10-Q).

Lantheus Holdings, Inc.

Consolidated Statements of Operations

(in thousands, except per share data – unaudited)

Lantheus Holdings, Inc.

Consolidated Revenues Analysis

(in thousands – unaudited)

Lantheus Holdings, Inc.

Reconciliation of GAAP to Non-GAAP Financial Measures

(in thousands, except per share data – unaudited)

Lantheus Holdings, Inc.

Reconciliation of Free Cash Flow

(in thousands – unaudited)

Lantheus Holdings, Inc.

Condensed Consolidated Balance Sheets

(in thousands – unaudited)

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