Analisa Coleman, 22, was last seen Thursday on the 900 block of West Wilson Avenue, police said.
She was recently diagnosed with epilepsy and schizophrenia, police said.
Coleman was described as a black woman with a medium complexion. She has black hair and brown eyes, and is 5 feet 2 inches tall and weighs 140 pounds, police said.
Anyone with information on Coleman's whereabouts should contact the Area North Special Victims Unit at (312) 744-8200.