Employees of large and small companies are likely to face higher health care costs, with increases in premiums, bigger deductibles or co-pays, and will possibly lose some benefits next year, according to a large survey of companies nationwide that was released on Thursday.

The survey of 1,700 companies, conducted by Mercer, a benefits consultant, indicated that employers are anticipating the sharpest increases in medical costs in about 15 years. Higher drug costs, rising hospital prices and greater demand for care are all contributing factors, experts said.

With the projected increases, this is the fourth consecutive year in which employers — and their workers — have faced significantly higher costs for health insurance, with next year representing the biggest jump since 2010.

A portion of the increases can still be traced to the lingering effects of the pandemic, but experts say the higher costs could represent a significant challenge. “I think affordability is a real issue for their work force,” said Ellen Kelsay, the chief executive of the Business Group on Health, which represents large employers that provide health insurance to their workers.

Without making any changes to benefits — which would involve moves like shifting more costs to workers or reducing benefits — employers said they expected next year’s increases in health costs to reach nearly 9 percent on average. By altering plans, they projected increases overall of 6.5 percent on average in health costs next year.

A quarter of those surveyed projected double-digit increases for 2026 even after changes to plans.

What will higher costs mean for workers?

While companies will impose a variety of measures to control health care costs, workers should expect their employers to pass on some of the burden.