Ironwood Pharmaceuticals Reports Third Quarter 2019 Results; Raises Full Year 2019 Guidance - - Total revenue of $131 million, driven primarily by LINZESS (linaclotide) U.S. collaboration revenue of

Ironwood Pharmaceuticals Reports Third

Quarter 2019 Results; Raises Full Year 2019 Guidance -

Total revenue of $131 million, driven primarily by LINZESS (linaclotide) U.S. collaboration revenue of $85 million and ex-U.S.

license and milestone revenue of $42 million -

$21 million in GAAP net income from continuing operations; $76 million in adjusted EBITDA from continuing operations -

LINZESS prescription demand continued to grow, achieving all-time highs during the period -

Phase II top-line data now expected mid-2020 vs 2H 2020 due to faster enrollment -

Mass., October 31, 2019 - Ironwood Pharmaceuticals, Inc. (Nasdaq: IRWD), a GI-focused healthcare company, today

provided an update on its third quarter 2019 results and recent business performance. Ironwood also announced that it is increasing

its full year 2019 total revenue and adjusted EBITDA from continuing operations guidance.

"We demonstrated solid execution during the third quarter

highlighted by further growth in LINZESS prescription demand, the continued advancement of our late-stage pipeline, and strong

operational performance," said Mark Mallon, chief executive officer of Ironwood. "LINZESS prescription demand grew

15% year-over-year - maintaining strong double-digit growth through the summer months. We also simplified our business by

successfully amending our linaclotide ex-U.S. partnerships in China and Japan, establishing a new U.S. commercial partnership with

Alnylam for givosiran in AHP, and restructuring our debt - all while continuing to deliver profits. As a result of this strong

performance, we look forward to building on this momentum as we strive to deliver value for all Ironwood stakeholders."

Third Quarter 2019 Financial Highlights1

(in thousands, except for per share amounts)

Third Quarter 2019 Corporate Highlights

Global Collaborations and U.S. Promotional Partnerships

Additional Business Updates

Third Quarter Financial Results

Ironwood 2019 Financial Guidance

Ironwood revised its 2019 financial guidance and

1 Revised 2019 guidance for total revenue

and Adjusted EBITDA from continuing operations reflects approximately $42.4 million in license and milestone payments related to

the amended ex-U.S. agreements with Astellas and AstraZeneca that were recognized in the third quarter of 2019.

2 Separation expenses were $6.7 million

in the third quarter of 2019.

3 Restructuring expenses were largely

incurred during the first quarter of 2019 in connection with the reduction in workforce commenced in February 2019. Total restructuring

adjustments in the third quarter of 2019 were $0.2 million.

4 Adjusted EBITDA from continuing operations

is calculated by subtracting net interest expense, taxes, depreciation, amortization, fair value of remeasurement of contingent

consideration, mark-to-market adjustments on derivatives related to Ironwood's 2022 Convertible Notes, impairment of intangibles,

restructuring expenses, separation expenses, and loss of extinguishment of debt from GAAP net income (loss) from continuing operations.

In the second quarter of 2019, Ironwood began reporting in its financial statements GAAP net income (loss) from continuing operations

which excludes discontinued operations related to Cyclerion.

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, the amortization of acquired intangible assets, the fair value remeasurement of contingent

consideration associated with Ironwood's U.S. license agreement with AstraZeneca for the exclusive rights to all

products containing lesinurad, and the impairment of intangible assets associated with Ironwood's subsequent notice of termination

of the lesinurad license agreement, if any. Ironwood also excludes restructuring, separation-related expenses and loss on extinguishment

of debt from non-GAAP net income (loss). These adjustments are reflected in the non-GAAP net income (loss) in the third quarter

of 2019 and 2018 presented in this press release. Non-GAAP adjustments are further detailed below:

Ironwood also presents adjusted EBITDA from continuing operations,

a non-GAAP measure. Adjusted EBITDA from continuing operations is calculated by subtracting net interest expense, taxes, depreciation,

amortization, fair value of remeasurement of contingent consideration, 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 net income (loss)

from continuing operations. The adjustments are made on a similar basis as described above related to non-GAAP net income (loss),

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 from continuing operations to net income (loss) from continuing operations on a GAAP basis,

please refer to the tables at the end of this press release. Ironwood does not provide guidance on GAAP net income (loss) from

continuing operations or a reconciliation of expected adjusted EBITDA from continuing operations to expected GAAP net income (loss)

from continuing operations because, without unreasonable efforts, it is unable to predict with reasonable certainty the non-GAAP

adjustments used to calculate adjusted EBITDA from continuing operations 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 net income (loss) from continuing operations for the guidance period.

Conference Call Information

Ironwood will host a conference call and webcast at 8:30 a.m.

Eastern Time on Thursday, October 31, 2019 to discuss its third quarter 2019 results and recent business activities. Individuals

interested in participating in the call should dial (866) 393-4306 (U.S. and Canada) or (734) 385-2616 (international) using conference

ID number 1683099. 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 October 31, 2019 running

through 11:59 p.m. Eastern Time on November 14, 2019. To listen to the replay, dial (800) 585-8367 (U.S. and Canada) or (416) 621-4642

(international) using conference ID number 1683099. 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).

We are also advancing two late-stage, first-in-category GI product

candidates: IW-3718 is a gastric retentive formulation of a bile acid sequestrant being developed for the potential treatment of

persistent gastroesophageal reflux disease, and MD-7246 is a delayed-release formulation of linaclotide that is being evaluated

as an oral, intestinal, non-opioid, pain-relieving agent for patients suffering from abdominal pain associated certain GI diseases.

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 abdominal 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.