NATURE OF BUSINESS	12 Months Ended
Dec. 31, 2016
NATURE OF BUSINESS.
NATURE OF BUSINESS	1. NATURE OF BUSINESS Organization Collegium Pharmaceutical, Inc. (the “Company”) was incorporated in Delaware in April 2002 and then reincorporated in Virginia in July 2014. The Company has its principal operations in Canton, Massachusetts. The Company is a specialty pharmaceutical company developing and commercializing next-generation abuse-deterrent products that incorporate the Company’s patented DETERx® technology platform for the treatment of chronic pain and other diseases. The Company’s first product, Xtampza ER®, or Xtampza, is an abuse-deterrent, extended-release, oral formulation of oxycodone, a widely prescribed opioid medication. In April 2016, the U.S. Food and Drug Administration (“FDA”) approved the Company’s new drug application (“NDA”) filing for Xtampza for the management of pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate. In June 2016, the Company announced the commercial launch of Xtampza. The Company’s operations are subject to certain risks and uncertainties. The principal risks include inability to successfully commercialize products, changing market conditions for products and product candidates (including development of competing products), changing regulatory environment and reimbursement landscape, negative outcome of clinical trials, inability or delay in completing clinical trials or obtaining regulatory approvals, the need to retain key personnel and protect intellectual property, patent infringement litigation and the availability of additional capital financing on terms acceptable to the Company. Public Offerings of Common Stock In May 2015, the Company closed an initial public offering (“IPO”) of its common stock, which resulted in the sale of 6,670,000 shares of its common stock at a public offering price of $12.00 per share, including 870,000 shares of common stock upon the exercise by the underwriters of their option to purchase additional shares at the public offering price. The Company received proceeds from the IPO of approximately $72,029 after deducting underwriting discounts, commissions and expenses payable by the Company. In April 2015, in connection with preparing for the IPO, the Company’s board of directors and shareholders approved a one‑for‑6.9 reverse split of the Company’s common stock. All common stock share and per share amounts in the financial statements have been retroactively adjusted for all periods presented to give effect to the reverse split of the Company’s common stock, including reclassifying an amount equal to the reduction in par value to additional paid‑in capital. In connection with the closing of the IPO, all of the Company’s outstanding convertible preferred stock and accrued dividends automatically converted to common stock in May 2015, resulting in an additional 12,591,463 shares of common stock of the Company becoming outstanding. The significant increase in common stock outstanding in May 2015 impacted the year-over-year comparability of the Company’s net loss per share calculations. In January 2016, the Company issued and sold in a public offering an aggregate of 2,750,000 shares of its common stock at $20.00 per share. The Company received net proceeds from this public offering of approximately $51,174, after deduction of underwriting discounts and commissions and expenses payable by the Company. In October 2016, the Company issued and sold in a public offering an aggregate of 5,750,000 shares of its common stock at $16.00 per share. The Company received net proceeds from this public offering of approximately $86,166, after deduction of underwriting discounts and commissions and expenses payable by the Company. Basis of Accounting The consolidated financial statements include the accounts of Collegium Pharmaceutical, Inc. (a Virginia corporation) as well as the accounts of Collegium Securities Corp. (a Massachusetts corporation), incorporated in December 2015, a wholly-owned subsidiary requiring consolidation, and are prepared in conformity with accounting principles generally accepted in the United States of America. All intercompany balances and transactions have been eliminated in consolidation. Liquidity The Company has experienced net losses and negative cash flows from operating activities since its inception, and as of December 31, 2016 and December 31, 2015, had an accumulated deficit of $223,184 and $129,008, respectively. The Company expects to continue to incur net losses in the foreseeable future. A successful transition to profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. The Company believes that its cash and cash equivalents at December 31, 2016, together with expected cash inflows from the commercialization of Xtampza will enable the Company to fund its operating expenses, debt service and capital expenditure requirements into 2019. The Company may never achieve profitability, and unless and until it does, the Company will continue to need to raise additional cash. Management intends to fund future operations through additional private or public debt or equity offerings, and may seek additional capital through arrangements with strategic partners or from other sources. If the Company is unable to obtain financing or increase profitability, the related lack of liquidity will have a material adverse effect on the Company’s operations and future prospects.

1. NATURE OF BUSINESS

Organization

Collegium Pharmaceutical, Inc. (the “Company”) was incorporated in Delaware in April 2002 and then reincorporated in Virginia in July 2014. The Company has its principal operations in Canton, Massachusetts. The Company is a specialty pharmaceutical company developing and commercializing next-generation abuse-deterrent products that incorporate the Company’s patented DETERx® technology platform for the treatment of chronic pain and other diseases. The Company’s first product, Xtampza ER®, or Xtampza, is an abuse-deterrent, extended-release, oral formulation of oxycodone, a widely prescribed opioid medication. In April 2016, the U.S. Food and Drug Administration (“FDA”) approved the Company’s new drug application (“NDA”) filing for Xtampza for the management of pain severe enough to require daily, around-the-clock, long-term opioid treatment and for which alternative treatment options are inadequate. In June 2016, the Company announced the commercial launch of Xtampza.

The Company’s operations are subject to certain risks and uncertainties. The principal risks include inability to successfully commercialize products, changing market conditions for products and product candidates (including development of competing products), changing regulatory environment and reimbursement landscape, negative outcome of clinical trials, inability or delay in completing clinical trials or obtaining regulatory approvals, the need to retain key personnel and protect intellectual property, patent infringement litigation and the availability of additional capital financing on terms acceptable to the Company.

Public Offerings of Common Stock

In May 2015, the Company closed an initial public offering (“IPO”) of its common stock, which resulted in the sale of 6,670,000 shares of its common stock at a public offering price of $12.00 per share, including 870,000 shares of common stock upon the exercise by the underwriters of their option to purchase additional shares at the public offering price. The Company received proceeds from the IPO of approximately $72,029 after deducting underwriting discounts, commissions and expenses payable by the Company.

In April 2015, in connection with preparing for the IPO, the Company’s board of directors and shareholders approved a one‑for‑6.9 reverse split of the Company’s common stock. All common stock share and per share amounts in the financial statements have been retroactively adjusted for all periods presented to give effect to the reverse split of the Company’s common stock, including reclassifying an amount equal to the reduction in par value to additional paid‑in capital.

In connection with the closing of the IPO, all of the Company’s outstanding convertible preferred stock and accrued dividends automatically converted to common stock in May 2015, resulting in an additional 12,591,463 shares of common stock of the Company becoming outstanding. The significant increase in common stock outstanding in May 2015 impacted the year-over-year comparability of the Company’s net loss per share calculations.

In January 2016, the Company issued and sold in a public offering an aggregate of 2,750,000 shares of its common stock at $20.00 per share. The Company received net proceeds from this public offering of approximately $51,174, after deduction of underwriting discounts and commissions and expenses payable by the Company.

In October 2016, the Company issued and sold in a public offering an aggregate of 5,750,000 shares of its common stock at $16.00 per share. The Company received net proceeds from this public offering of approximately $86,166, after deduction of underwriting discounts and commissions and expenses payable by the Company.

Basis of Accounting

The consolidated financial statements include the accounts of Collegium Pharmaceutical, Inc. (a Virginia corporation) as well as the accounts of Collegium Securities Corp. (a Massachusetts corporation), incorporated in December 2015, a wholly-owned subsidiary requiring consolidation, and are prepared in conformity with accounting principles generally accepted in the United States of America. All intercompany balances and transactions have been eliminated in consolidation.

Liquidity

The Company has experienced net losses and negative cash flows from operating activities since its inception, and as of December 31, 2016 and December 31, 2015, had an accumulated deficit of $223,184 and $129,008, respectively. The Company expects to continue to incur net losses in the foreseeable future. A successful transition to profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure.

The Company believes that its cash and cash equivalents at December 31, 2016, together with expected cash inflows from the commercialization of Xtampza will enable the Company to fund its operating expenses, debt service and capital expenditure requirements into 2019. The Company may never achieve profitability, and unless and until it does, the Company will continue to need to raise additional cash. Management intends to fund future operations through additional private or public debt or equity offerings, and may seek additional capital through arrangements with strategic partners or from other sources. If the Company is unable to obtain financing or increase profitability, the related lack of liquidity will have a material adverse effect on the Company’s operations and future prospects.