Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 14, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Trading Symbol	ALDX
Entity Registrant Name	ALDEYRA THERAPEUTICS, INC.
Entity Central Index Key	0001341235
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		26,244,434