Ironwood Pharmaceuticals Reports Fourth Quarter and Full Year 2023 Results; Achieves 2023 Financial Guidance - LINZESS (Iinaclotide) 2023 U.S. net sales of $1.1 billion, an increase of 7% year-over-

Ironwood Pharmaceuticals Reports Fourth Quarter

and Full Year 2023 Results; Achieves 2023 Financial Guidance

- LINZESS (Iinaclotide)

2023 U.S. net sales of $1.1 billion, an increase of 7% year-over-year, driven by EUTRx prescription demand growth of 10% year-over-year

- 2023 Ironwood revenue of $443 million,

driven primarily by $430 million in U.S. LINZESS collaboration revenue -

- Continues to expect topline results

from the STARS Phase III study of apraglutide in patients with short bowel syndrome with intestinal failure (SBS-IF) in March of

BOSTON, Mass., February 15,

2024 - Ironwood Pharmaceuticals, Inc. (Nasdaq: IRWD), a GI-focused healthcare company, today reported its

fourth quarter and full year 2023 results and recent business performance.

"In 2023, we made important progress toward realizing our vision

to become the leading GI healthcare company in the industry," said Tom McCourt, chief executive officer of Ironwood. "In

its 11th year on market, LINZESS had another terrific year as the leading prescription treatment for adults with IBS-C or

chronic idiopathic constipation, with prescription demand increasing a robust 10% year-over-year. In June of 2023, LINZESS received

FDA approval for functional constipation in pediatric patients ages 6 to 17, becoming the first and only prescription therapy for this

patient population. In addition, we strengthened our GI pipeline with the addition of apraglutide. We believe apraglutide has the potential

to improve the standard of care for patients with short bowel syndrome dependent on parenteral support, if approved, as the only once-weekly

GLP-2 therapy, and achieve $1 billion dollars in peak net sales. Looking ahead in 2024, we remain focused on maximizing LINZESS, advancing

our GI pipeline and delivering sustained profits and cash flows. We are excited about the continued strong LINZESS performance and the

key pipeline catalysts ahead of us, highlighted by the topline data from our STARS Phase 3 study expected in March and topline data

from the ongoing Phase 2 study for CNP-104 expected in the third quarter, which we believe can propel Ironwood's next phase of

growth and create value for patients and shareholders in the years to come."

Fourth Quarter and Full Year 2023 Financial Highlights1

(in thousands, except for per share amounts)

Fourth Quarter and Full Year 2023 Corporate Highlights

Fourth Quarter and Full Year 2023 Financial

1 Adjusted EBITDA is calculated by subtracting restructuring

expenses, net interest expense, income taxes, depreciation and amortization, and acquisition-related costs from GAAP net income. For

purposes of the 2024 guidance, Ironwood has assumed it will not incur material expenses related to business development activities

in 2024 and excludes any costs associated with potential CNP-104 option exercise. Ironwood does not provide guidance on GAAP net income

or a reconciliation of expected adjusted EBITDA to expected GAAP net income because, without unreasonable efforts, it is unable to predict

with reasonable certainty the non-GAAP adjustments used to calculate adjusted EBITDA. These adjustments are uncertain, depend on various

factors and could have a material impact on GAAP net income for the guidance period. Management believes this non-GAAP information is

useful for investors, taken in conjunction with Ironwood's GAAP financial statements, because it provides greater transparency

and period-over-period comparability with respect to Ironwood's operating performance. These measures are also used by management

to assess the performance of the business. Investors should consider these non-GAAP measures only as a supplement to, not as a substitute

for or as superior to, measures of financial performance prepared in accordance with GAAP. In addition, these non-GAAP financial measures

are unlikely to be comparable with non-GAAP information provided by other companies.

Non-GAAP Financial Measures

Ironwood presents non-GAAP net income and non-GAAP net income per

share to exclude the impact, net of tax effects, of net gains and losses on derivatives related to Ironwood's 2022 Convertible

Notes that are required to be marked-to-market, amortization of acquired intangible assets, restructuring expenses, and acquisition-related

costs. Non-GAAP adjustments are further detailed below:

Ironwood also presents adjusted EBITDA, a non-GAAP measure, as well

as guidance on adjusted EBITDA. Adjusted EBITDA is calculated by subtracting mark-to-market adjustments on derivatives related to Ironwood's

2022 Convertible Notes, restructuring expenses, net interest expense, income taxes, depreciation and amortization, and acquisition-related

costs from GAAP net income. The adjustments are made on a similar basis as described above related to non-GAAP net income, as applicable.

Management believes this non-GAAP information is useful for investors,

taken in conjunction with Ironwood's GAAP financial statements, because it provides greater transparency and period-over-period

comparability with respect to Ironwood's operating performance. These measures are also used by management to assess the performance

of the business. Investors should consider these non-GAAP measures only as a supplement to, not as a substitute for or as superior to,

measures of financial performance prepared in accordance with GAAP. In addition, these non-GAAP financial measures are unlikely to be

comparable with non-GAAP information provided by other companies. For a reconciliation of non-GAAP net income and non-GAAP net income

per share to GAAP net income and GAAP net income per share, respectively, and for a reconciliation of adjusted EBITDA to GAAP net income,

please refer to the tables at the end of this press release.

Ironwood does not provide guidance on GAAP net income or a reconciliation

of expected adjusted EBITDA to expected GAAP net income because, without unreasonable efforts, it is unable to predict with reasonable

certainty the non-GAAP adjustments used to calculate adjusted EBITDA. These adjustments are uncertain, depend on various factors

and could have a material impact on GAAP net income for the guidance period.

Conference Call Information

Ironwood will host a conference call

and webcast at 8:30 a.m. Eastern Time on Thursday, February 15, 2024 to discuss its fourth quarter and full year 2023 results

and recent business activities. Individuals interested in participating in the call should dial +1 (888) 596-4144 (U.S. and Canada) or

(647) 495-7514 (international) using conference ID number and event passcode 1057375. To access the webcast, please visit the Investors

section of Ironwood's website at www.ironwoodpharma.com at least 15 minutes prior to the start of the call to ensure adequate time

for any software downloads that may be required. The call will be available for replay via telephone starting at approximately 11:30

a.m. Eastern Time on February 15, 2024, running through 11:59 p.m. Eastern Time on February 29, 2024. To listen

to the replay, dial (800) 770-2030 (U.S. and Canada) or (647) 362-9199 (international) using conference ID number 1057375. The archived

webcast will be available on Ironwood's website for 1 year beginning approximately one hour after the call has completed.

About Ironwood Pharmaceuticals

Ironwood Pharmaceuticals (Nasdaq: IRWD), an S&P

SmallCap 600 company, is a leading gastrointestinal (GI) healthcare company on a mission to advance the treatment of GI diseases

and redefine the standard of care for GI patients. We are pioneers in the development of LINZESS (linaclotide), the U.S. branded

prescription market leader for adults with irritable bowel syndrome with constipation (IBS-C) or chronic idiopathic constipation (CIC).

LINZESS is also approved for the treatment of functional constipation in pediatric patients ages 6-17 years-old. Ironwood is also advancing

apraglutide, a next-generation, long-acting synthetic GLP-2 analog being developed for rare gastrointestinal diseases, including short

bowel syndrome with intestinal failure (SBS-IF) as well as several earlier stage assets. Building upon our history of GI innovation,

we keep patients at the heart of our R&D and commercialization efforts to reduce the burden of GI diseases and address significant

Founded in 1998, Ironwood Pharmaceuticals

is headquartered in Boston, Massachusetts, and has an additional site in Basel, Switzerland.

routinely post information that may be important to investors on our website at www.ironwoodpharma.com.

About LINZESS (Linaclotide)

LINZESS is the #1 prescribed brand in the U.S. for the treatment

of adult patients with irritable bowel syndrome with constipation ("IBS-C") or chronic idiopathic constipation ("CIC"),

based on IQVIA data.

LINZESS is a once-daily capsule that helps relieve the abdominal pain,

constipation, and overall abdominal symptoms of bloating, discomfort and pain associated with IBS-C, as well as the constipation, infrequent

stools, hard stools, straining, and incomplete evacuation associated with CIC. LINZESS relieves constipation in children and adolescents

aged 6 to 17 years with functional constipation. The recommended dose is 290 mcg for IBS-C patients and 145 mcg for CIC patients, with

a 72 mcg dose approved for use in CIC depending on individual patient presentation or tolerability. In children with functional constipation

aged 6 to 17 years, the recommended dose is 72 mcg.

LINZESS is not a laxative; it is the first medicine approved by the

FDA in a class called GC-C agonists. LINZESS contains a peptide called linaclotide that activates the GC-C receptor in the intestine.

Activation of GC-C is thought to result in increased intestinal fluid secretion and accelerated transit and a decrease in the activity

of pain-sensing nerves in the intestine. The clinical relevance of the effect on pain fibers, which is based on nonclinical studies,

has not been established.