While you're still working, your employer generally helps cover at least part of your health care insurance/costs (hopefully!). But the moment that you stop working, you'll be responsible for the entire cost.
If you retire before age 65, you will pay full market rates in your area for all health insurance and related costs. The total cost of this coverage could be a far greater than you expect, and you would be wise to research those costs as you create a reliable retirement plan, and before making the decision of when to retire.
Once you are age 65, you will be eligible for Medicare, which will help with some basic health care costs, but it is not totally free. In general, an otherwise healthy individual may pay ~ $110 per month for basic coverage (Medicare Part B), plus an additional $80 per month if they include additional doctors services (Medicare Part C)and prescription coverage (Medicare Part D). Medicare Parts C and D are both optional coverage, but they are highly recommended. Add in some basic co-pay amounts and deductibles, and the total cost could easily be a minimum of $300 - $400 per month. And that's for those in good health. $400 per month for health care costs, or $800 per month for couples, is no small amount, and must be included in any retirement plan. Over the course of 25 years, that amounts to $120,000 ($240,000 for couples) before any inflation adjustment. Many would argue that that's on the low end of potential costs.
But wait, there's more (unfortunately). The U.S. Department Of The Actuary is forecasting that health care costs will increase at a rate of ~ 6% per year, for at least the next decade. That's more than 2.75x the historical inflation rate over the past 20 years (2.13%). Using $400 per month in costs, and an inflation rate of 2.5%, the total needed for 25 years of retirement would be almost $178,000 ($356,00 for couples). Using an inflation rate of 6%, that total becomes almost $301,000 ($602,000 for couples). Not accounting for the higher forecasted inflation rate for health care costs could result in a $123,000 ($246,000 for couples) impact on your retirement savings.
If you're an individual who is saving $1,000 a month for retirement (with a 5% return), it will take you an additional 7 years of saving just to account for the higher inflation rate (6%) for health care costs. Not a pleasant thought, but better to know now so that you can plan accordingly.
It also may inspire you to write to your Congressman/Congresswoman to express your concerns!