Tens of millions of Americans are straining under the burden of two jobs: the work they’re paid to do, and the task of providing care for older family members.

The double shift can come at a career cost. Caregivers who are also working full time report turning down promotions or seeking less-demanding assignments. Some switch companies, or say they’ve had to choose care duties over their careers.

Rich Bueler Jr., a 37-year sales manager at a large company, retired early a few years back. He had the money. He also had to care for his 89-year-old parents. His demanding job lacked the flexibility he needed to both work and be available to his parents.

“I threw up my hands,” says Bueler. “I wasn’t mad. I was discouraged and disappointed.”

An estimated 29 million workers, from senior managers to retail clerks, work while also caring for an adult family member , according to research by AARP and the National Alliance for Caregiving. Six out of 10 are working full time, compared with 46% in 2009. After working 40 hours, many spend about 20 hours providing unpaid care, according to the research.

Care demands on workers are growing because people are living longer with chronic illness. A simple fall or unexpected cancer diagnosis can lead to hospital stays, months of treatment and worry throughout. Plus, a large share of people want to age at home but need lots of help from family members to do so.

Company benefits often don’t include senior or eldercare support, such as paid time off or reimbursed care, or accommodate those exhausted by caring for a person in failing health. Some working caregivers have been called in to talk with their bosses about performance. Others say they haven’t used a vacation day for actual vacation in years.

“My work doesn’t stop,” says Kim Moser, who manages a research lab at the University of Oklahoma while also caring for her 83-year-old mother-in-law. “There is no off switch.”

The breaking point

Two years ago, Bueler, now 65, noticed that his parents were declining in memory and mobility and needed more frequent help. They lived close by, so he would come over a few times a week to help fill pill containers, get them to doctors’ appointments and take them to the grocery store, outings that could consume several hours.

Bueler, who lives in Ballwin, Mo., checked his corporate benefits online and found nothing related to eldercare. The human-resources department, he says, told him the only benefit available was the Family and Medical Leave Act, which is required by law, but didn’t fit his needs because his parents didn’t need daily care.

He asked his manager if there was a more flexible position that would employ his skills but require less-frequent customer and partner meetings. He says he was advised to search the company’s job board for postings.

Tensions can run high between employees and employers over caregiving. Bosses might assume that a worker who is also caregiving will be distracted, or won’t meet deadlines, or will have to leave unexpectedly for an undetermined amount of time.

Federal laws provide limited protection from discrimination against workers who care for family members with a chronic or disabling condition, but some states and local laws offer more protection to family caregivers.

Cynthia Thomas Calvert, a senior adviser for the Center for WorkLife Law, says workplace discrimination against employees who care for adult family members is an escalating problem.

“We expect further growth as the population ages,” says Calvert, who also works with employers to support working caregivers.

Few good options

People who work at smaller companies or nonprofits, where remote work isn’t an option, often rely on the goodwill of their supervisors.

Ollie Lewis, 47, manages a Volunteers of America Thrift store in Westland, Mich., arriving at 8 a.m. and overseeing a team of 35 employees. He also cares for his mom, who has had breast cancer and a stroke and was recently diagnosed with Parkinson’s disease and dementia.

Ollie, an only child , assumed his mother’s care after his dad died eight years ago. He uses paid time off and lunch breaks to take her to the doctor or physical therapy.

During a recent annual retreat for managers, he received a call that his mom was in the emergency room and unresponsive. He told the district manager, Carmen Nieves, he was leaving. She has assured him she will open his store and close it if he needs to be with his mom, an assurance he says provides him peace of mind.

“I know she will be there if I really need her,” he says.

More than one-third of working caregivers said they plan to leave work primarily because of caregiving, according to a recent survey by AARP and S&P Global. Others can’t afford to forgo a paycheck, because of mortgages and college expenses, and push themselves to extremes.

About half of employees who left a job because of caregiving were senior executives and leaders, according to a 2024 Harvard Business School report.

Companies, which have long offered maternity and paternity benefits to attract and retain workers, are beginning to offer support for those caring for older family members. About half of employers said senior benefits were a priority this year, up from 43% in 2023, according to a survey by Care.com, an online family-care platform.

Some companies allow employees to add their parents to their health insurance plans or connect them with care specialists. Citigroup recently announced two weeks of paid leave annually to care for an immediate family member. The most prized benefit, according to employee surveys, is flexibility.

The unexpected

Kim Moser, the lab manager in Oklahoma, and her husband, Greg, juggle their work schedules so someone is always at home with his mom, Charlene.

A few months ago, Greg, 56, who works at night as a custodial manager at the university, broke his foot. Kim had to take care of them both. She began going into the lab after dinner, sometimes starting at 8 p.m. and working through the night.

That arrangement eventually became a problem because Kim was needed at the lab during the day to help students. Her lab does genetic research on worms. Kim orders supplies for the lab and also conducts her own experiments.

She says her supervisor was understanding, but called her into his office to say the students needed her in the lab to mentor them. They talked about a way she could do that and still provide care at home.

“It was the first time I have ever been called into my supervisor’s office to discuss whether my home life was affecting my work life,” says Kim, who has worked at the university for 23 years and is the family’s main breadwinner.

Kim and Greg discussed options that evening. She had accumulated hours of paid leave but didn’t want to use them. She has diabetes and high blood pressure and wanted to make sure they were available if she herself got sick.

With her supervisor’s support, she arranged to have students give her their schedules. That way she could coordinate her own schedule to be in the lab when they were.

At home, Kim cooks meals most evenings for the family. She also makes sure Charlene takes her medications and does her exercises.

“I need a lot of help,” says Charlene, who says her memory is getting worse and she falls frequently. “I know it’s hard on them, but they do their best.”

The stress of trying to work and provide care took an emotional toll. Kim has already exhausted the number of hours allotted to her for mental-health counseling as part of her insurance.

“I had some rough patches,” she says.

Write to Clare Ansberry at clare.ansberry@wsj.com