Beth, who's been battling a throat cancer recurrence since late last year, had trouble breathing and passed out briefly before being hospitalized.
Sources told TMZ that Beth's family is "preparing for the worst" and that many of her loved ones, including her mother, children and grandchildren, flew out to be by her side.
Previous reports claimed that Beth was uncooperative with doctors during her treatment and tried ripping out tubes used to give her medications and necessary fluids. Duane, 66, admitted as much in December 2018, when he revealed that Beth wasn't listening to her doctors and wanted to explore alternative therapies.
Beth was first diagnosed with throat cancer in 2017. She was declared cancer-free after removing a tumor but was later diagnosed with stage 4 lung cancer.
Beth wrote on Instagram in February that she was testing out CBD and THC-based therapies and alleged that chemotherapy was "poison." In April, Beth was hospitalized for similar breathing issues that led to her emergency treatment last weekend.
Duane previously told Fox News the couple, who starred in their hit A&E reality television show from 2004 until 2012, credits faith with helping them survive.
"Faith is probably the No. 1 thing in our lives, no matter what we’re faced with... Through this cancer episode, we had to drum up as much faith as we could. And the Bible talks about having faith as small as a mustard seed," he said. "And that’s not much... And I thank God that we had at least that much faith to get her through that."
On Monday, the Chapmans' rep told The Associated Press that Beth remained hospitalized in a coma, noting, “Duane and the family feel she’s such a fighter, she could get better. The family still has hope.”
The Associated Press and Fox News' Nicole Darrah contributed to this report.