Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 01, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	Acer Therapeutics Inc.
Entity Central Index Key	0001069308
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Trading Symbol	ACER
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		10,087,363
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2019