Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 21, 2020	Jun. 30, 2019
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Registrant Name	GALECTIN THERAPEUTICS INC
Entity Central Index Key	0001133416
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Trading Symbol	GALT
Entity Public Float			$ 166
Entity Common Stock, Shares Outstanding		57,031,027
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Interactive Data Current	Yes
Entity Address, State or Province	GA
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Warrant [Member]
Document Information [Line Items]
No Trading Symbol Flag	true
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ
Common Stock [Member]
Document Information [Line Items]
No Trading Symbol Flag	true
Title of 12(b) Security	Common Stock
Security Exchange Name	NASDAQ