Ironwood Pharmaceuticals Reiterates Full-Year 2025 LINZESS U.S. Net Sales Guidance and Raises Adjusted EBITDA Guidance - Reiterates 2025 guidance of LINZESS U.S. net sales of $800-$850 million and t

Ironwood Pharmaceuticals Reiterates Full-Year

2025 LINZESS U.S. Net Sales Guidance and Raises Adjusted EBITDA Guidance

- Reiterates 2025 guidance of LINZESS U.S. net sales of $800-$850 million and total Ironwood revenue of $260-290 million -

- LINZESS (Iinaclotide) EUTRx prescription demand growth in Q1 2025 of 8% year-over-year; in line with full-year expectations -

- Raises adjusted EBITDA to greater than $105 million for 2025 -

Mass., April 25, 2025 - Ironwood Pharmaceuticals, Inc. (Nasdaq: IRWD), a biotechnology company developing and

commercializing life-changing therapies for people living with gastrointestinal (GI) and rare diseases, today announced it reiterates

its full year 2025 LINZESS U.S. net sales and total Ironwood revenue guidance and raises its adjusted EBITDA guidance. Ironwood plans

to report full first quarter 2025 results in early May.

"Today, we are reiterating our full-year 2025 LINZESS U.S. net

sales and total Ironwood revenue guidance. In the first quarter of 2025, we saw continued strong prescription demand growth of 8% year-over-year,

which was offset by anticipated pricing headwinds as well as a change in estimate of AbbVie gross-to-net rebate reserves, which was refined

to reflect rebates owed for units dispensed in the first quarter of 2025. We do not expect first quarter LINZESS U.S. net sales results

or this change in estimate to impact the full-year results," said Tom McCourt, chief executive officer of Ironwood. "In addition,

we have raised our full-year 2025 adjusted EBITDA guidance to greater than $105 million as we no longer plan to make certain apraglutide

commercial launch planning investments and will shift our focus to the confirmatory Phase 3 trial, consistent with the recent FDA feedback."

Continued Strong Demand for U.S. LINZESS

2025 Financial Guidance. Ironwood is reiterating its 2025 U.S. LINZESS net sales and total revenue guidance and is raising

its adjusted EBITDA financial guidance.

U.S. collaborative arrangements revenue includes reimbursement from AbbVie for a portion of Ironwood's commercial expenses related

to sales of LINZESS in the U.S. The FY2025 total revenue guidance accounts for the impact of the reduction to Ironwood's commercial

expenses and corresponding reimbursement from AbbVie due to Ironwood's strategic reorganization announced in January 2025.

EBITDA is calculated by subtracting restructuring expenses, net interest expense, income taxes, depreciation and amortization and stock-based

compensation, from GAAP net income. The exclusion of stock-based compensation from Adjusted EBITDA represents an update to our definition

of Adjusted EBITDA, effective in the first quarter of 2025. For purposes of this guidance, we have assumed that Ironwood will not incur

material expenses related to business development activities in 2025. 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.

About Ironwood Pharmaceuticals

Ironwood Pharmaceuticals (Nasdaq: IRWD) is a biotechnology

company developing and commercializing life-changing therapies for people living with gastrointestinal (GI) and rare diseases. Ironwood

is advancing apraglutide, a next-generation, long-acting synthetic GLP-2 analog being developed for short bowel syndrome patients who

are dependent on parenteral support. In addition, Ironwood has been a pioneer 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. Building upon

our history of innovation, we keep patients at the heart of our R&D and commercialization efforts to reduce the burden of diseases

and address significant unmet needs.

Founded in 1998, Ironwood Pharmaceuticals is headquartered

in Boston, Massachusetts, with a 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.

In the United States, Ironwood and AbbVie co-develop and co-commercialize

LINZESS for the treatment of adults with IBS-C or CIC. In Europe, AbbVie markets linaclotide under the brand name CONSTELLA for the

treatment of adults with moderate to severe IBS-C. In Japan, Ironwood's partner, Astellas, markets linaclotide under the brand name LINZESS

for the treatment of adults with IBS-C or CIC. Ironwood also has partnered with AstraZeneca for development and commercialization of LINZESS

in China, and with AbbVie for development and commercialization of linaclotide in all other territories worldwide.

LINZESS Important Safety Information

INDICATIONS AND USAGE

LINZESS (linaclotide) is indicated for the treatment of both irritable

bowel syndrome with constipation (IBS-C) and chronic idiopathic constipation (CIC) in adults and functional constipation (FC) in children

and adolescents 6 to 17 years of age. It is not known if LINZESS is safe and effective in children with FC less than 6 years of age or

in children with IBS-C less than 18 years of age.

IMPORTANT SAFETY INFORMATION

Warnings and Precautions

Adverse Reactions (incidence 2% and greater than placebo)

Please see full Prescribing Information including Boxed Warning:

LINZESS and CONSTELLA are registered trademarks of Ironwood

Forward-Looking Statements

This press release contains forward-looking statements within the meaning

of the Private Securities Litigation Reform Act of 1995. Investors are cautioned not to place undue reliance on these forward-looking

statements, including statements about Ironwood's ability to execute on its mission; Ironwood's strategy, business, financial

position and operations; Ironwood's financial performance and results, and guidance, expectations related thereto and expected timing

to provide full first quarter 2025 results; LINZESS prescription demand growth, LINZESS U.S. net sales growth, total revenue and adjusted

EBITDA in 2025; Ironwood's expectation that the change in AbbVie's estimate of gross-to-net rebate reserves will impact the

quarterly phasing of LINZESS U.S. net sales but not the full-year results; that moving forward, gross-to-net rebate reserves will continue

to be based on rebates owed for units dispensed by channel in each applicable quarter; Ironwood's expectation that rebates owed

for units dispensed in subsequent quarters will offset the Q1 2025 change in estimate impact and will not have impact for the full year;

; and Ironwood's plan to no longer to make certain commercial launch planning investments for apraglutide and to shift its focus

to the confirmatory Phase 3 trial. These forward-looking statements speak only as of the date of this press release, and Ironwood undertakes

no obligation to update these forward-looking statements. Each forward-looking statement is subject to risks and uncertainties that could

cause actual results to differ materially from those expressed or implied in such statement. Applicable risks and uncertainties include

those related to the effectiveness of development and commercialization efforts by us and our partners; preclinical and clinical development,

manufacturing and formulation development of linaclotide, apraglutide, IW-3300, and our other product candidates; the risk of uncertainty

relating to pricing and reimbursement policies in the U.S., which, if not favorable for our products, could hinder or prevent our products'

commercial success; the risk that healthcare reform and other governmental and private payor initiatives may have an adverse effect upon

or prevent our products' or product candidates' commercial success; the risk that apraglutide will not be approved by the

FDA or other regulatory agencies; the risk that clinical programs and studies, including for linaclotide pediatric programs, apraglutide

and IW-3300, may not progress or develop as anticipated, including that studies are delayed or discontinued for any reason, such as safety,

tolerability, enrollment, manufacturing, economic or other reasons; the risk that findings from our ongoing and completed nonclinical