A process for producing internally coated glass tubes

A method for manufacturing a glass tube with a tempered inner surface by drawing a glass melt (5) to a hose (8) of softened glass and hot forming to a glass tube (9), in which method in the hose (8) is introduced a substance of softened glass characterized in that the substance is introduced as an aerosol and the inner surface is compensated by means of the substance during the hot forming, so that the hydrolytic resistance of the coated inner surface or delivery of the coated inner surface of sodium ions to water compared with an untreated inner surface by at least 10% is improved or reduced.