A sustained release dosage form comprises an active ingredient blended with a polymeric matrix. At least a portion of the polymeric matrix is formed by a cellulose ether having an onset dissolution temperature of at least 40° C., having anhydroglucose units joined by 1-4 linkages and having methyl groups, hydroxyalkyl groups, and optionally alkyl groups being different from methyl as substituents such that the cellulose ether has an MS (hydroxyalkyl) of 0.05 to 1.00, and hydroxyl groups of anhydroglucose units are substituted with methyl groups such that [s23/s26−0.2*MS(hydroxyalkyl)] is 0.31 or less, wherein s23 is the molar fraction of anhydroglucose units wherein only the two hydroxyl groups in the 2- and 3-positions of the anhydroglucose unit are substituted with a methyl group and wherein s26 is the molar fraction of anhydroglucose units wherein only the two hydroxyl groups in the 2- and 6-positions of the anhydroglucose unit are substituted with a methyl group.