Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2023	May 08, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Entity Registrant Name	EQUILLIUM, INC.
Entity Central Index Key	0001746466
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		34,414,149
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Trading Symbol	EQ
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-38692
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-1554746
Entity Address, Address Line One	2223 Avenida de la Playa
Entity Address, Address Line Two	Suite 105
Entity Address, City or Town	La Jolla
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92037
City Area Code	858
Local Phone Number	412-5302
Document Quarterly Report	true
Document Transition Report	false