A method for obtaining aqueous formulations with easily oxidizable active principles, notably phenols, stable over a prolonged period, comprising subjecting them to extreme deoxygenation by bubbling with an inert gas and/or placing wider vaccum, protecting them against possible resorption of oxygen by keeping them under an inert gas atmosphere, by filling, under inert gas, into bottles previously cleared of air by insufflation with inert gas, then subjecting them, while stoppering, to low pressure as obtained in the bottle, of 65,000 Pa maximum, to obtain aqueous solutions having a residual oxygen concentration in the solution below 2 ppm, and preferably of the order of 1 ppm and even 0.5 ppm useful as injectable preparations having an oxygen concentration in the solution below 2 ppm.