The rapper's show in Santa Ana, Calif., that was scheduled for Tuesday night was nixed, with the venue blaming a "medical emergency" for the cancellation, TMZ reported.
His concerts in Los Angeles Wednesday and in San Diego on Thursday are also reportedly expected to be postponed.
Friends of DMX are reportedly worried about his health and concerned he has relapsed following previous struggles with substance abuse.
Sources told TMZ that DMX had been drinking heavily during a Ruff Ryders reunion concert at the Barclays Center in Brooklyn over the weekend.
DMX was hospitalized a little over a year ago after cops found him unconscious and no longer breathing at a Ramada Inn parking lot in Yonkers.
Police said at the time that a victim who had ingested "some sort of substance" had been rescued in the parking lot of the hotel, but did not identify them by name. The patient was given Narcan, which is used to treat an overdose.
DMX has spoken about his troubles with drugs in the past, telling Dr. Phil in 2013 that he became addicted after smoking a blunt laced with cocaine when he was 14.