What are the serious side effects of bilastine?

Could you elaborate on the potential severe side effects of bilastine usage? Are there any specific health concerns that patients should be aware of before taking this medication? Additionally, what actions should be taken if any of these side effects manifest, and is it crucial to seek medical attention immediately in such cases? Furthermore, are there any factors that may increase the risk of experiencing these adverse reactions, such as pre-existing conditions or interactions with other medications?