Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2022	Feb. 21, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K/A
Amendment Flag	true
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Registrant Name	PROMETHEUS BIOSCIENCES, INC.
Entity Central Index Key	0001718852
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 872.7
Entity Common Stock, Shares Outstanding		47,530,337
Entity File Number	001-40187
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-4282653
Entity Address, Address Line One	3050 Science Park Road
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	422-4300
ICFR Auditor Attestation Flag	true
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	RXDX
Security Exchange Name	NASDAQ
Document Annual Report	true
Document Transition Report	false
Auditor Name	BDO USA, LLP
Auditor Location	San Diego, CA
Auditor Firm ID	243
Amendment Description	Unless the context requires otherwise, references in this report to “Prometheus,” the “Company,” “we,” “us” and “our” refer to Prometheus Biosciences, Inc. On February 28, 2023, the Company filed its Annual Report on Form 10-K for the fiscal year ended December 31, 2022 (the Original Form 10-K). Certain Part III information was omitted from the Original Form 10-K in reliance on General Instruction G(3) to Form 10-K. General Instruction G(3) to Form 10-K provides that registrants may incorporate by reference certain information from a definitive proxy statement which involves the election of directors if such definitive proxy statement is filed with the Securities and Exchange Commission (the SEC) within 120 days after the end of the fiscal year. We are filing this Amendment No. 1 (this Amendment) to include Part III information in the Original Form 10-K because we do not expect to file a definitive proxy statement containing this information within 120 days after the end of the fiscal year covered by the Original Form 10-K. Accordingly, this Amendment hereby amends and restates Part III, Items 10 through 14, of the Original Form 10-K as set forth below. This Amendment also restates Item 15 of Part IV of the Original Form 10-K. In addition, as required by Section 302 of the Sarbanes-Oxley Act of 2002 (SOX) and Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the Exchange Act), new certifications by our principal executive officer and principal financial officer are filed as exhibits to this Amendment under Item 15 of Part IV hereof. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4, and 5 of the certifications have been omitted. We are not including the certifications under Section 906 of SOX as no financial statements are being filed with this Amendment. No other amendments are being made hereby to the Original Form 10-K. Except as stated herein, this Amendment does not reflect events occurring after the filing of the Original Form 10-K with the SEC on February 28, 2023, and no attempt has been made in this Amendment to modify or update other disclosures as presented in the Original Form 10-K.
Documents Incorporated by Reference	None.

Prometheus Biosciences, Inc. 10-K/A