Ironwood Pharmaceuticals Reports Strong Second-Quarter 2021 Results, Raises Full-Year Guidance - LINZESS (Iinaclotide) U.S. net sales of $259 million, an increase of 18% year-over-year - - Total rev

Ironwood Pharmaceuticals Reports Strong Second-Quarter

2021 Results, Raises Full-Year Guidance

- LINZESS (Iinaclotide)

U.S. net sales of $259 million,

an increase of 18% year-over-year -

of $104 million, an increase of 16% year-over-year,

driven primarily by U.S. LINZESS collaboration revenue of $100 million -

of $391 million, includes a $338 million non-recurring income tax

benefit related to the release of the valuation allowance against the

majority of the company's deferred tax assets -

ended Q2 2021 with $493 million in cash and cash equivalents -

Mass., August 5, 2021 - Ironwood Pharmaceuticals, Inc. (Nasdaq: IRWD), a GI-focused healthcare company, today reported

financial results for second quarter 2021 and raised full year 2021 financial guidance.

Commenting on the results, Tom McCourt, chief

executive officer of Ironwood, said: "Continued exceptional execution behind a sound strategy resulted in another outstanding quarter

for Ironwood. Building on the momentum of LINZESS and its impressive growth, we remain in a position of strength and confident in our

future growth prospects. I am proud of our experienced leadership team and employees who continue to maintain laser focus on our strategic

priorities in order to deliver important medicines to patients and value to our shareholders."

Second Quarter 2021 Financial Highlights1

(in thousands, except for per share amounts)

Second Quarter 2021 Corporate Highlights

U.S. Promotional Partnerships

Second Quarter Financial Results

Ironwood is raising its 2021 financial guidance due to the

growth in U.S. LINZESS prescription demand. The Company now expects:

1 Adjusted EBITDA is calculated by subtracting net interest

expense, income taxes, depreciation, amortization, mark-to-market adjustments on derivatives related to Ironwood's 2022 Convertible

Notes and restructuring expenses from GAAP net income.

Non-GAAP Financial Measures

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

share to exclude the impact of net gains and losses on derivatives related to Ironwood's 2022 Convertible Notes that are required

to be marked-to-market, restructuring expense, and the release of the Company's valuation allowance against the majority of deferred

tax assets. 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, income taxes, depreciation, amortization,

mark-to-market adjustments on derivatives related to Ironwood's 2022 Convertible Notes and restructuring expenses 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, August 5, 2021 to discuss its second quarter 2021 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

and event passcode 2598317. 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 August 5, 2021 running through

11:59 p.m. Eastern Time on August 19, 2021. To listen to the replay, dial (800) 585-8367 (U.S. and Canada) or (416) 621-4642

(international) using conference ID number 2598317. 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 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). Under the guidance of our seasoned industry leaders, we

continue to build upon our history of GI innovation and challenge what has been done before to shape what the future holds. We keep patients

at the heart of our R&D and commercialization efforts to reduce the burden of GI diseases and address significant unmet needs.

Founded in 1998, Ironwood Pharmaceuticals is headquartered in

Boston, Massachusetts.

We routinely post information that may be important to investors on

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. 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 worldwide.

LINZESS Important Safety Information

INDICATIONS AND USAGE

LINZESS (linaclotide) is indicated in adults for the treatment of