Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Aug. 04, 2022
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2022
Document Transition Report	false
Entity File Number	001-35853
Entity Registrant Name	BIOSTAGE, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-5210462
Entity Address, Address Line One	84 October Hill Road, Suite 11
Entity Address, City or Town	Holliston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01746
City Area Code	774
Local Phone Number	233-7300
Title of 12(b) Security	None
No Trading Symbol Flag	true
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 Common Stock, Shares Outstanding		11,615,642
Entity Central Index Key	0001563665
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Amendment Flag	false