Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 30, 2020
Document and Entity Information
Entity Registrant Name	CATABASIS PHARMACEUTICALS INC
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	CATB
Security Exchange Name	NASDAQ
Document Type	10-Q
Document Period End Date	Sep. 30, 2020
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		20,084,337
Entity Central Index Key	0001454789
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false