Cover - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 21, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2021
Current Fiscal Year End Date	--12-31
Entity File Number	001-39555
Entity Registrant Name	GREENWICH LIFESCIENCES, INC.
Entity Central Index Key	0001799788
Entity Tax Identification Number	20-5473709
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	3992 Bluebonnet Dr.
Entity Address, Address Line Two	Building 14
Entity Address, City or Town	Stafford
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77477
City Area Code	(832)
Local Phone Number	819-3232
Title of 12(b) Security	Common Stock
Trading Symbol	GLSI
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	true
Elected Not To Use the Extended Transition Period	false
Entity Shell Company	false
Entity Public Float			$ 171,492,883
Entity Common Stock, Shares Outstanding		12,951,453
Auditor Name	MaloneBailey, LLP
Auditor Firm ID	206
Auditor Location	Houston, Texas