Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Feb. 28, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K/A
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-34962
Entity Registrant Name	ZOGENIX, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-5300780
Entity Address, Address Line One	5959 Horton Street
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Emeryville
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94608
City Area Code	510
Local Phone Number	550-8300
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	ZGNX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 863.0
Entity Common Stock, Shares Outstanding		56,228,303
Documents Incorporated by Reference	None.
Entity Central Index Key	0001375151
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Amendment Flag	true
Amendment Description	Zogenix, Inc., referred to in this report as “Zogenix,” “the Company,” “we,” “us,” and “our,” is filing this Amendment No. 1 on Form 10-K/A (the “Amendment”) to its Annual Report on Form 10-K for the year ended December 31, 2021, originally filed on March 1, 2022 (the “Original Report”), for the sole purpose of including the information required by Part III of Form 10-K. This information was previously omitted from the Original Report in reliance on General Instruction G(3) to Form 10-K, which permits the information in the below referenced items to be incorporated in the Form 10-K by reference from our definitive proxy statement if such statement is filed no later than 120 days after our fiscal year end. We are filing this Amendment to provide information required in Part III of Form 10-K for the fiscal year ended December 31, 2021, because a definitive proxy statement containing such information will not be filed by the Company within 120 days after the end of the fiscal year covered by the Form 10-K. In accordance with Rule 12b-15 under the Securities and Exchange Act of 1934, as amended (the “Exchange Act”), Part III, Items 10 through 14 of the Original Report are hereby amended and restated in their entirety, and Part IV, Item 15 of the Original Report is hereby amended and restated only with respect to the addition of the new certifications by our principal executive officer and principal financial officer filed herewith. This Amendment does not reflect events occurring after the filing of the Original Report, does not modify or update in any way the disclosures contained in the Original Report, and does not modify or update those disclosures that may be affected by subsequent events. Accordingly, this Amendment should be read in conjunction with the Original Report and with our filings with the Securities and Exchange Commission (“SEC”) subsequent to the Original Report. As previously disclosed in our Current Report on Form 8-K, filed with the SEC on January 19, 2022, on January 18, 2022, the Company, UCB S.A., a société anonyme formed under the laws of Belgium (“Parent”), and Zinc Merger Sub, Inc., a Delaware corporation and an indirect wholly owned subsidiary of Parent (“Merger Sub”), entered into a definitive Agreement and Plan of Merger (the “Merger Agreement”), pursuant to which Parent, through Purchaser, commenced a tender offer (the “Offer”) on February 1, 2022 to acquire all of the outstanding shares of the Company’s common stock, par value $0.001 per share, at a purchase price of (a) $26.00 per Company Share, net to the holder thereof, in cash, without interest thereon plus (b) one contingent value right per Company Share representing the right to receive a contingent payment of $2.00, net to the holder thereof, in cash, without interest thereon, upon the achievement of the milestone.
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	Redwood City, California