Psychosis can have a range of symptoms, but the most common are hallucinations and delusions. In a hallucination, you perceive something that isn’t there. Hallucinations can be felt with any of the five senses. For example, you may see a person who isn’t really there, or smell smoke when there isn’t any. Delusions are strong beliefs that don’t match reality. For example, you may believe that you’re being followed or that you’re communicating with powerful forces, such as aliens or deities.