Autistic children have difficulties in adapting their language for particular listeners and contexts. We asked whether these difficulties are more prominent when children are required to be cognitively flexible, when changing how they have previously referred to a particular object. We compared autistic (N = 30) with neuro-typical 5- to 7-year-olds. Each child participated in two conditions. In the switch condition, the same animal had to be re-described across trials to be appropriately informative (e.g. a participant could appropriately describe a picture as 'dog' on one trial but later the participant needed to re-describe the same picture as 'spotty dog' to differentiate it from a co-present black dog). In the no-switch condition, no picture needed to be re-described. Nonetheless, the conditions were matched regarding the requirement to use both complex (e.g. spotty cat) versus simple expressions (e.g. horse). Autistic children were more over-informative than peers even prior to the requirement to re-describe an animal. Overall, we found a main effect of the switch condition and no interaction with group. Switching a description hinders the ability of children to be appropriately informative. As autistic children are generally less appropriately informative, the requirement to switch leads to particularly poor performance in autism.