Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Aug. 10, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	Acer Therapeutics Inc.
Entity Central Index Key	0001069308
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Trading Symbol	ACER
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		10,052,988
Document Fiscal Period Focus	Q2
Document Fiscal Year Focus	2018