Taylor, 77, who has long suffered from ill health, was taken to a Los Angeles hospital from her Beverly Hills home on Monday.
New York Post columnist Cindy Adams says Taylor is still deeply grieving for Jackson, who died suddenly in June aged 50.
"The heart's gone out of her," Adams said in her column.
"She's suffering weakness, tiredness, exhaustion, emotional draining. She hasn't stopped crying. She and Michael were devoted to one another."
Taylor had been preparing to travel to London for Jackson's comeback tour when she was told he had died "and she began screaming." Adams also said the Jackson family had denied her access to his funeral and memorial because she was Michael's friend, not theirs.
After Jackson died, Taylor said: "I loved Michael with all my soul and I can't imagine life without him."
Taylor was a vocal supporter of Jackson during his trial for child molestation charges, of which he was acquitted.
