Ardelyx Reports 2017 Financial Results and Appoints Industry Veteran Jan Lundberg, Ph.D. to Board of Directors Enrollment Underway in Second Registration Study of Tenapanor for Hyperphosphatemia NDA for Tenapanor for IBS

Ardelyx Reports 2017 Financial Results and Appoints Industry Veteran Jan Lundberg, Ph.D. to Board of

Enrollment Underway in Second Registration Study of Tenapanor for Hyperphosphatemia

NDA for Tenapanor for IBS-C on Track for Submission in Second Half of 2018

FREMONT, Calif., March 14, 2018 Ardelyx, Inc. (NASDAQ: ARDX), today reported pipeline highlights and financial results for

the fourth quarter and full-year ended December 31, 2017. In addition, industry-leading research expert Jan M. Lundberg, Ph.D. has been appointed to the company s board of directors, effective March 23, 2018.

Jan s extensive research expertise positions him as an invaluable addition to the Ardelyx team, and we are delighted that he is joining our board.

We look forward to leveraging his substantial experience, as he has been involved in the discovery, development and approval of more than 20 products, said Mike Raab, president and chief executive officer of Ardelyx. As we look ahead,

our focus is on addressing the significant need for new treatments for patients with renal diseases by developing first-in-class, small molecule medicines, as with

tenapanor for hyperphosphatemia and our RDX013 program for hyperkalemia. We believe that the combination of our proprietary drug discovery platform, renal drug development capabilities and our plans for a specialized U.S. commercial approach

targeting nephrologists, positions Ardelyx to meaningfully change the care of many patients, while creating value for shareholders.

tenapanor represents a more than $1 billion market opportunity for both hyperphosphatemia and IBS-C, added Reg Seeto, MBBS, chief operating officer of Ardelyx. For our renal pipeline, our plan

is to deploy our internal expertise to bring tenapanor to the U.S. market on our own, while leveraging strategic collaborations to bring it to markets outside the U.S. For IBS-C, we intend to leverage

collaborations to bring tenapanor to patients globally. Our collaborations with KHK in Japan and Fosun Pharma in China are each off to a strong start, and we look forward to evaluating additional opportunities to expand the reach of our novel

Full Year 2017 Financial Results

Ardelyx is focused on enhancing the

way people with renal diseases are treated by developing first-in-class medicines. Ardelyx s renal pipeline includes the Phase 3 development of tenapanor for the

treatment of hyperphosphatemia in people with end-stage renal disease who are on dialysis and RDX013, a potassium secretagogue program for the potential treatment of high potassium, or hyperkalemia, a problem

among certain patients with kidney and/or heart disease. In addition,

Ardelyx has completed Phase 3 development of tenapanor for the treatment of irritable bowel syndrome with constipation and anticipates submitting a New Drug Application to the U.S. Food and Drug

Administration for this indication in the second half of 2018. To efficiently bring its treatments to market, Ardelyx is pursing strategic collaborations in the U.S. and other countries, with established agreements with KHK in Japan and Fosun Pharma

in China. For more information, please visit www.ardelyx.com/ and connect with us on Twitter @Ardelyx.

Forward Looking Statements

To the extent that statements contained in this press release are not descriptions of historical facts regarding Ardelyx, they are forward-looking statements

reflecting the current beliefs and expectations of management made pursuant to the safe harbor of the Private Securities Reform Act of 1995, including the potential for Ardelyx s product candidates in treating the diseases and conditions for

which they are being developed; Ardelyx s expected timing for the filing of its NDA for tenapanor for the treatment of IBS-C, Ardelyx s expected timing to receive topline data for its second Phase 3

trial of tenapanor for the treatment of hyperphosphatemia in patients with end-stage renal disease who are on dialysis, the potential for Ardelyx to receive milestone and royalty payments from Shanghai Fosun

Pharmaceutical Industrial Development and Kyowa Hakko Kirin Co., Ltd and Ardelyx s ability to establish collaborations in the future. Such forward-looking statements involve substantial risks and uncertainties that could cause the development

of Ardelyx s product candidates or Ardelyx s future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, the

uncertainties inherent in research and the clinical development process, including the regulatory approval process. Ardelyx undertakes no obligation to update or revise any forward-looking statements. For a further description of the risks and

uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to Ardelyx s business in general, please refer to Ardelyx s Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 14, 2018, and its future current and periodic reports to be filed with the Securities and Exchange Commission.

Monique Allaire, THRUST IR

Alicia Davis, THRUST IR

Consolidated Condensed Balance Sheets

Consolidated Statements of Operations

(In thousands, except share and per share amounts)