Even though the majority of companies have realised the benefits of implementing sustainability practices into their business strategies today, the problem is that the marketing of these activities still has a negative impact on the environment. Therefore, the purpose of this research is to examine if the impact of sustainable advertisements can influence the purchase decisions of young adults who show loyalty to another brand. In order to reach this purpose, qualitative research was conducted using an abductive approach through 23 semi-structured individual interviews with consumers between the ages of 19-30. This enabled us to get an in-depth understanding of their subjective consumption behaviour in comparison to sustainable advertisements. This report draws on existing literature which states that sustainability promotions positively impact the consumer decision process and that consumers’ rarely switch from a brand they are highly loyal to. The results show that sustainable advertisements' impact on young adults is dependent on the product-involvement category. In order for sustainable advertisements to have a chance to generate a switching behaviour among young adults for high-involvement products, the message must provide clear and transparent information regarding the product, because the perception of brands tends to be more valuable. However, this is not as important for low-involvement products since sustainable messages can provoke a switching behaviour based on emotional appeals. Therefore, this research contributes to companies which seek to use sustainable marketing for high- or low-involvement products.