Ironwood Pharmaceuticals Reports Strong Third Quarter 2020 Results and Increases Full Year 2020 Financial Guidance - U.S. LINZESS (linaclotide) net sales increased 10% year-over-year to $241 million

Pharmaceuticals Reports Strong Third Quarter 2020 Results and

Increases Full Year 2020 Financial Guidance

U.S. LINZESS (linaclotide) net sales increased 10% year-over-year to $241 million,

as reported by AbbVie Inc. (AbbVie) -

U.S. LINZESS collaboration revenue to Ironwood increased 18% year-over-year to $100 million, resulting in 3Q 2020 total Ironwood

revenue of $103 million -

3Q 2020 GAAP net income was $34 million and adjusted EBITDA was $47 million -

Expect total cost savings of approximately $95 million, excluding anticipated one-time costs, relating to discontinuation of

IW-3718 and planned workforce reduction -

BOSTON, Mass., November 5, 2020 - Ironwood

Pharmaceuticals, Inc. (Nasdaq: IRWD), a GI-focused healthcare company, today provided an update on its third quarter

2020 results and recent business performance.

financial performance this quarter was bolstered by continued demand for our market leading product LINZESS, which delivered

10% growth in net sales year-over-year, and another quarter of profitability and positive cash flow for Ironwood," said

Mark Mallon, chief executive officer of Ironwood. "While our pipeline experienced disappointing setbacks, we are

confident that under the seasoned leadership of our talented, GI-experienced team, we are positioned well to execute against

our strategic priorities. Through our focused efforts, we seek to unlock meaningful shareholder value as we progress our

mission of advancing GI medicines and redefining the standard of care for GI patients."

Quarter 2020 Financial Highlights1

(in thousands, except for per share amounts)

Quarter 2020 Corporate Highlights

Global Collaborations and U.S. Promotional Partnerships

Third Quarter Financial Results

1 Adjusted EBITDA is calculated by subtracting

net interest expense, taxes, depreciation, amortization, mark-to-market adjustments on derivatives related to Ironwood's

2022 Convertible Notes, restructuring expenses, separation expenses, and loss on extinguishment of debt from GAAP income from continuing

operations, net of income taxes.

Non-GAAP Financial Measures

Ironwood presents non-GAAP net income (loss) and non-GAAP net

income (loss) per share to exclude the impact of net gains and losses on derivatives related to our 2022 Convertible Notes that

are required to be marked-to-market. Ironwood also excludes restructuring, separation-related expenses, and loss on extinguishment

of debt from non-GAAP net income (loss), if any. These adjustments, as applicable, are reflected in the non-GAAP net income (loss)

in the third quarter 2020 presented in this press release. 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 net interest expense, taxes, depreciation,

amortization, mark-to-market adjustments on derivatives related to Ironwood's 2022 Convertible Notes, restructuring expenses,

separation expenses and loss on extinguishment of debt from GAAP income from continuing operations, net of income taxes. The adjustments

are made on a similar basis as described above related to non-GAAP net income (loss), 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

(loss) and non-GAAP net income (loss) per share to GAAP net income (loss) and GAAP net income (loss) per share, respectively, and

for a reconciliation of adjusted EBITDA to income from continuing operations, net of income taxes on a GAAP basis, please refer

to the tables at the end of this press release.

Ironwood does not provide guidance on GAAP income from continuing

operations, net of income taxes or a reconciliation of expected adjusted EBITDA to expected GAAP income from continuing operations,

net of income taxes because, without unreasonable efforts, it is unable to predict with reasonable certainty the non-GAAP adjustments

used to calculate adjusted EBITDA including, without limitation, the mark-to-market adjustments on the derivatives related to its

2022 Convertible Notes. These adjustments are uncertain, depend on various factors and could have a material impact on GAAP

income from continuing operations, net of income taxes for the guidance period.

Conference Call Information

Ironwood will host a conference call and webcast at 4:30 p.m. Eastern

Time on Thursday, November 5, 2020 to discuss its third quarter 2020 results and recent business activities. Individuals interested

in participating in the call should dial (833) 350-1432 (U.S. and Canada) or (647) 689-6932 (international) using conference ID

number 2794527. 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 7:30 p.m. Eastern Time on November 5, 2020

running through 11:59 p.m. Eastern Time on November 19, 2020. To listen to the replay, dial (800) 585-8367 (U.S. and

Canada) or (416) 621-4642 (international) using conference ID number 2794527. The archived webcast will be available on Ironwood's

website for 14 days beginning approximately one hour after the call has completed.

About Ironwood Pharmaceuticals

Ironwood Pharmaceuticals (Nasdaq: IRWD) is a GI-focused healthcare

company dedicated to creating medicines that make a difference for patients living with GI diseases. We discovered, developed and

are commercializing linaclotide, the U.S. branded prescription market leader for adults with irritable bowel syndrome with constipation

(IBS-C) or chronic idiopathic constipation (CIC).

Ironwood was founded in 1998 and is headquartered in Boston,

Mass. For more information, please visit our website at www.ironwoodpharma.com or www.twitter.com/ironwoodpharma;

information that may be important to investors will be routinely posted in both these locations.

About LINZESS (linaclotide)

prescribed brand for the treatment of adult patients with irritable bowel syndrome with constipation (IBS-C) and chronic idiopathic

constipation (CIC), based on IQVIA data.

LINZESS is a once-daily

capsule that helps relieve the overall abdominal symptoms (bloating, discomfort and pain) and constipation associated with IBS-C,

as well as the constipation, infrequent stools, hard stools, straining, and incomplete evacuation associated with CIC. 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. LINZESS should be taken at least 30 minutes before the first meal of the day.

LINZESS is contraindicated

in pediatric patients less than 6 years of age. The safety and effectiveness of LINZESS in pediatric patients less than 18 years

of age have not been established. In neonatal mice, linaclotide increased fluid secretion as a consequence of guanylate

cyclase-C (GC-C) agonism resulting in mortality within the first 24 hours due to dehydration.

Due to increased intestinal expression of GC-C, patients less than 6 years of age may be more likely than patients 6 years of age

and older to develop severe diarrhea and its potentially serious consequences. In adults with IBS-C or CIC treated with LINZESS,

the most commonly reported adverse event was diarrhea.

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

Important Safety Information