Cunningham had been undergoing drug rehabilitation at Dr. Drew Pinksy's Pasadena Recovery Center outside of Los Angeles, the same place where London will get treatment as part of VH1's Celebrity Rehab 4.
"Thankfully she was under the supervision of health professionals and was immediately transported to a nearby hospital where she received the medical attention she required," the Party of Five actor's rep, Dominic Friesen, tells PEOPLE.
"Jeremy remains her strongest supporter as she pursues sobriety under the care of the Center," adds the rep.
Cunningham was released from the hospital and has returned to rehab.
The couple's stint in rehab comes a month after he alleged he was kidnapped at gunpoint by men who had helped him fix a flat tire in Palm Springs and forced him to do drugs
His family has questioned the series of events and said London needs "psychological help."
Reporting by KEN LEE