Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Feb. 28, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Document Transition Report	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity File Number	001-31791
Entity Registrant Name	GALECTIN THERAPEUTICS INC.
Entity Central Index Key	0001133416
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	04-3562325
Entity Address, Address Line One	4960 Peachtree Industrial Blvd
Entity Address, Address Line Two	Suite 240
Entity Address, City or Town	Norcross
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30071
City Area Code	678
Local Phone Number	620-3186
Title of 12(b) Security	Common Stock, $0.001 Par Value Per Share
Trading Symbol	GALT
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 139
Entity Common Stock, Shares Outstanding		59,357,893
ICFR Auditor Attestation Flag	false
Auditor Firm ID	677
Auditor Name	CHERRY BEKAERT LLP
Auditor Location	Atlanta, Georgia