The digitalization of the healthcare sector has expanded and changed how actors in a healthcare journey experience mental healthcare. One significant change is how symptom assessment is conducted, specifically the digital transformation of self-assessment tools and models. New ways of assessing symptoms elicit challenges for designers working with digital mental healthcare. Challenges exist in developing and transforming self-assessment tools to fit a digital environment. This study takes a qualitative approach to explore what challenges designers might face while working with digital self-assessment tools. The study method consists of seven open interviews where thematic analysis was used to interpret themes representing design challenges. The identified themes are immutable tools and models, limited user involvement in design, regulatory barriers and official requirements, and multiple actors in design work. The themes highlight design challenges working with self-assessment tools and are represented through data extracts and discussed with identified relevant literature. Understanding design challenges could help designers make informed decisions while working with digital self-assessment services and tools