Some people with dementia may experiences hallucinations. Not everyone with dementia will be affected in this way, and not everyone who experiences these problems has dementia.
People with dementia can also experience 'visual mistakes', such as illusions, misperceptions and misidentifications. These are different from hallucinations, though they are sometimes mistaken for them.
For more information see factsheet 527, Sight, perception and hallucinations in dementia.