Incomplete Freund’s Adjuvant (IFA) is a water-in-oil emulsion that is similar to the Complete Freund’s Adjuvant (CFA) without addition of heat-killed mycobacteria (Mycobacterum butyricum).

IFAVax consists of a mixture of mineral oil and emulsifier in a ratio of 85% v/v oil and 15% v/v emulsifier. Importantly, the IFAVax is not a pre-formed emulsion and thus it must be mixed with an equal volume of aqueous solution of antigen and subsequently emulsified prior to use. The emulsifier is mannide monooleate, an ester consisting of mannitol as the hydrophilic residue and oleic acid (unsaturated C18 fatty acid) as the hydrophobic part.