BELLUS Health : Corporate Presentation – December 2021

Investor Presentation

NASDAQ/TSX - BLU

December 21st, 2021

Forward Looking Statements

Certain statements contained in this presentation, other than statements of fact that are independently verifiable at the date hereof, may constitute "forward-looking statements" within the meaning of Canadian securities legislation and regulations, the U.S. Private Securities Litigation Reform Act of 1995, as amended, and other applicable securities laws. Forward-looking statements are frequently, but not always, identified by words such as "expects," "anticipates," "believes," "intends," "estimates," "potential," "possible," "projects," "plans," and similar expressions. Such statements, based as they are on the current expectations of management, inherently involve numerous important risks, uncertainties and assumptions, known and unknown, many of which are beyond the control of BELLUS Health Inc. ("BELLUS Health"). Such statements include, but are not limited to, the potential of BLU-5937 to successfully treat refractory chronic cough ("RCC") and other hypersensitization-related disorders and benefit such patients, BELLUS Health's expectations related to its preclinical studies and clinical trials, including the design, timing and results of its Phase 2b SOOTHE clinical trial of BLU-5937 in RCC, including the timing and outcome of interactions with regulatory agencies, the potential activity and tolerability profile, selectivity, potency and other characteristics of BLU-5937, including as compared to other competitor candidates, the timing of initiation of its Phase 3 clinical trial of BLU-5937 in RCC, the commercial potential of BLU-5937, including with respect to patient population, pricing and labeling, BELLUS Health's intention to discontinue development of BLU-5937 in pruritic conditions and the Phase 2a proof-of-concept BLUEPRINT trial, BELLUS Health's financial position, and the potential applicability of BLU-5937 and BELLUS Health's P2X3 platform to treat other disorders. Risk factors that may affect BELLUS Health's future results include but are not limited to: the benefits and impact on label of its enrichment strategy, estimates and projections regarding the size and opportunity of the addressable RCC market for BLU-5937, the ability to expand and develop its project pipeline, the ability to obtain adequate financing, the ability of BELLUS Health to maintain its rights to intellectual property and obtain adequate protection of future products through such intellectual property, the impact of general economic conditions, general conditions in the pharmaceutical industry, the impact of the ongoing COVID-19 pandemic on BELLUS Health's operations, plans and prospects, including to the initiation and completion of clinical trials in a timely manner or at all, changes in the regulatory environment in the jurisdictions in which BELLUS Health does business, supply chain impacts, stock market volatility, fluctuations in costs, changes to the competitive environment due to consolidation, achievement of forecasted burn rate, potential payments/outcomes in relation to indemnity agreements and contingent value rights , achievement of forecasted preclinical study and clinical trial milestones, reliance on third parties to conduct preclinical studies and clinical trials for BLU-5937 and that actual results may differ from topline results once the final and quality-controlled verification of data and analyses has been completed. In addition, the length of BELLUS Health's product candidate's development process and its market size and commercial value are dependent upon a number of factors. Moreover, BELLUS Health's growth and future prospects are mainly dependent on the successful development, patient tolerability, regulatory approval, commercialization and market acceptance of its product candidate BLU-5937 and other products. Consequently, actual future results and events may differ materially from the anticipated results and events expressed in the forward-looking statements. BELLUS Health believes that expectations represented by forward-looking statements are reasonable, yet there can be no assurance that such expectations will prove to be correct. The reader should not place undue reliance, if any, on any forward-looking statements included in this presentation. These forward-looking statements speak only as of the date made, and BELLUS Health is under no obligation and disavows any intention to update publicly or revise such statements as a result of any new information, future event, circumstances or otherwise, unless required by applicable legislation or regulation. Please see BELLUS Health's public filings with the Canadian securities regulatory authorities, including, but not limited to, its Annual Information Form, and the United States Securities and Exchange Commission, including, but not limited to, its Annual Report on Form 40-F, for further risk factors that might affect BELLUS Health and its business. Please see BELLUS

Health's public filings with the Canadian securities regulatory authorities, including, but not limited to, its Annual Information Form, and the United States Securities and Exchange Commission, including, but not limited to, its Annual Report on Form 40-F, for further risk factors that might affect BELLUS Health and its business.

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Company Overview

BELLUS Overview

BLU-5937: Highly Selective, Second Generation P2X3 Antagonist for Hypersensitization Disorders

Lead Indication - Refractory Chronic Cough (RCC)

• Population estimated at 9M in U.S.; Significant unmet need
• Compelling efficacy and tolerability topline results from SOOTHE Phase
  2b trial:
• • 34% placebo-adjusted reduction in 24H cough frequency and 53% reduction from baseline at 50 and 200 mg BID doses

Key Expected 2022 Events

• FDA End of Phase 2 meeting - 2Q 2022
• Start of Phase 3 - 2H 2022
• First generation P2X3 antagonist FDA Advisory Committee - 1Q 2022

• • Improvement in patient-reported outcomes
  • Well-tolerated;adverse event profile comparable to placebo
• Interactions with regulatory agencies and start of global Phase 3 program expected in 2022

Pipeline in a Product

• Potential to study BLU-5937 in other cough-related hypersensitivity populations
• Potential for applicability in other hypersensitization disorders; 3 non- cough indications in Phase 2 with a third-party P2X3 antagonist*

Intellectual Property

• Composition of Matter patents granted to 2034
• 100% ownership of global rights

Financials

~$246M cash position**

* Three indications (pain related to endometriosis, overactive bladder and neuropathic pain) in development by a third party.
** As of September 30, 2021 and proforma to $200M financing priced on Dec 14th, 2021.	4

Strong Leadership and Advisory Group

Management

Roberto Bellini

President & Chief Executive Officer

Dr. Catherine Bonuccelli, MD

Chief Medical Officer

Ramzi Benamar, MBA

Chief Financial Officer

Dr. Denis Garceau, PhD

Chief Scientific Officer

Tony Matzouranis

Senior Vice President, Business

Development

Board of Directors

Dr. Francesco Bellini, PhD	Roberto Bellini
Chair
Dr. Youssef Bennani, PhD	Franklin Berger
Dr. Clarissa Desjardins, PhD	Pierre Larochelle
Dr. Bill Mezzanotte, MD, PhD	Joseph Rus

Clinical Advisory Board

CHRONIC COUGH

Dr. Jacky Smith (Chair) , MB, ChB, FRCP, PhD	Dr. Michael S. Blaiss, MD
Manchester University	Medical College of Georgia
Dr. Surinder Birring, MB ChB (Hons), MD	Dr. Peter Dicpinigaitis, MD
King's College London	Albert Einstein Medical College

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