Annual report pursuant to Section 13 and 15(d)

Document and Entity Information

v3.21.1
Document and Entity Information - USD ($)
 12 Months Ended
Dec. 31, 2020
Mar. 15, 2021
Jun. 30, 2020
Cover [Abstract]      
Entity Registrant Name Greenwich LifeSciences, Inc.    
Entity Central Index Key 0001799788    
Document Type 10-K    
Document Period End Date Dec. 31, 2020    
Amendment Flag false    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filer 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    
Entity Ex Transition Period false    
ICFR Auditor Attestation Flag false    
Entity Shell Company false    
Entity Public Float     $ 0
Entity Common Stock, Shares Outstanding   12,846,897  
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2020