This chapter presents answers to the most common misconceptions regarding the safety of aluminium (Al) compounds in vaccines by providing an overview of what is currently known about Al adjuvants, in particular, and their modes of action and mechanisms of potential toxicity. It gives a brief overview of the crucial role of Al in a variety of neurological disorders and then elaborates on the unresolved controversy about Al adjuvant safety. Al adjuvants exert their immunostimulatory effect through many different actions, which impinge on both the innate and adaptive immune systems. Some of the actions are activation of the NLRP3 inflammasome pathway, and protection of antigens, resulting in prolonged delivery. The risks associated with vaccine‐derived Al are threefold: it can persist in the body, it can trigger pathological immunological responses, and it can make its way into the central nervous system (CNS).