One-time real estate agent Evelyn Rehg was showing a house to a prospective buyer four years ago when an alarming phone call came from the retirement facility where her mother lived.
"They told me I either had to get my mother immediately into a mental hospital or she would be evicted," said Rehg, 48, of Crestwood, Missouri.
"I panicked," she added. "I didn't know how to handle it insurance-wise, what hospital to take her to or anything like that."
Rehg is a member of the so-called sandwich generation, generally defined as those in their 40s and 50s who are squeezed between caring for both their own children and their aging parents. The financial and emotional cost of care can be overwhelming.
Rehg's mother, 80, suffers from mild dementia, severe anxiety and manic behaviors that now are treated properly. But prior to the phone call, her mom's anxiety had become so debilitating that she began calling Rehg's cell phone upward of 200 times a day.
In desperation, Rehg, then still working in real estate, changed her number because she needed her phone for work. So instead, her mother started incessantly calling the front desk at the retirement facility.
"They put up with it for about a day and a half," Rehg said. "Then they called me."
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Rehg also has two children, who were then 12 and 9 and needed supervision and care. That meant that her husband, Jon, had to adjust his work schedule to tend to their needs.
Financial advisors say that in addition to the emotional drain, "sandwichers" may also face a financial burden if they haven't taken an interest in the steps parents have put in place to ensure they receive proper care.
"It's important to talk about financial things, but allow your parents some space," said Rita Cheng, a certified financial planner and chief executive of Blue Ocean Global Wealth.
"You don't need to be completely involved in their business, because they still want to be independent and in charge," she said. "But ultimately, if they want to be in charge of how they are cared for, they need to be proactive and plan for it."
Some of the things parents should organize include a list of all assets and debts, income and expenses; all insurance policies; their will; power-of-attorney assignment and anything else that pertains to their finances and care preferences.
"They need to plan for things [such as serious illness], even though planning for it doesn't mean it will happen," said Cheng, a sandwicher herself. "But if they don't plan, it doesn't mean it won't happen."
According to 2013 data from the Pew Research Center, nearly half of adults in the sandwich generation have a parent 65 or older and are either raising a young child or financially supporting an adult child.
About 15 percent of them are providing financial support to both an aging parent and a child.
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In Rehg's case, her father had assigned her power of attorney, and she met with his accountant prior to his death, which occurred about nine months before Rehg moved her mother into the retirement facility. Her mom increasingly was struggling alone in the house, where she had lived for decades.
After the call that made it clear that her mom's condition had deteriorated, Rehg checked her into a mental health facility. It was the first of a handful that Rehg had researched before her mother received a diagnosis and effective medication.
But then her mom fell and broke her arm and spent several months in a rehab center. She then lived in Rehg's house for about six months, until the situation became too challenging for the whole family.
Rehg, who by then had given up her real estate license, eventually found a suitable assisted-living facility and moved her mother there.
But in the process, Rehg depleted her parents' life savings to pay for the high level of care that her mother required. At one point, she was chipping in about $800 of her own money each month.
Gregory W. Edwards, a CFP and partner at Lawless Edwards & Warren Wealth Management, is also in the sandwich generation. His father, who had lived next door to him since 2001, died in 2011 after losing his battle with Alzheimer's disease.
His dad was financially well-equipped to pay for his care, but Edwards organized it—and it was complicated, because his father's wishes stated that he never wanted to be put in a nursing home.
During the last two years of his dad's life, the cost to care for him in his own home was $7,000 to $8,000 monthly.
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Additionally, Edwards and a brother each now give their mother, who was divorced from his father years ago, about $1,800 a month toward her various expenses, medical and otherwise.
Edwards recommends that people look into a life insurance policy that allows up to 50 percent of death benefits to be used toward care for those who meet certain requirements.
"People have no idea of what's coming down the pike when it comes to the cost of care in the last months of life," he said.
For many sandwichers, the pressures from the parent side outweigh those from the child side.
The hardest part is feeling overwhelmed and overworked. Sometimes you have to make hard choices and you have to be patient with yourself.Rita Chengchief executive of Blue Ocean Global Wealth
Rehg said that without her husband, she doesn't know how she could have managed the situation.
"It was the hardest thing I've ever been through in my life," she said. "At the height of it, I was probably spending 40 hours a week on my mom—paying bills, talking to doctors, visiting her, medicines—and trying to work 30 to 40 hours a week and take care of the house and two kids."
Cheng at Blue Ocean Global Wealth said that it is a difficult balancing act.
"The hardest part is feeling overwhelmed and overworked," she said. "I have to give myself permission that I'm only one person and this is stressful. Sometimes you have to make hard choices and you have to be patient with yourself," Cheng added.
—By Sarah O'Brien, special to CNBC.com.