Autonomous vehicles (AVs) are transforming transportation, shifting drivers into passive passengers. However, this shift raises challenges, including degraded situational awareness (SA) and increased motion sickness (MS). This review analyzes 50 relevant studies to explore existing strategies that utilize multimodal interactions to mitigate MS and enhance SA, while also examining the reciprocal relationship between MS and SA. The findings reveal that MS negatively impacts SA by increasing cognitive load and physiological discomfort, whereas strategies designed to enhance SA can indirectly alleviate MS by reducing sensory conflicts. Visual modalities and multimodal designs incorporating visual elements are the most widely adopted among these strategies. Integrating virtual reality (VR) in such designs also demonstrates a growing trend. Furthermore, the review evaluates the effectiveness of these strategies and identifies limitations, such as the lack of realism in experimental settings and insufficient attention to diverse user needs. This review integrates methods for mitigating MS and enhancing SA, providing a theoretical foundation and practical guidance for optimizing future human-vehicle interactions, and offering recommendations for designing safer and more comfortable autonomous driving experiences.