With out-of-pocket health insurance costs rising, it might seem like a good idea to buy an insurance policy that covers expenses that might not be paid by your health insurance if you are diagnosed with a serious condition.

Such policies, known as critical illness insurance, are increasingly being offered by employers along with life insurance, disability insurance, and other kinds of insurance. According to Aflac, 44 percent of employers now offer critical illness insurance, up from 24 percent just five years ago.

While more companies are offering the insurance, it’s often not clear to consumers whether they should buy it.

“Companies that provide this coverage should fully disclose the risks and the likelihood you would ever use it,” says Timothy Jost, law professor emeritus at Washington and Lee University. “There needs to be protection for consumers to ensure that they’re getting value for their coverage.”

Employees typically pay the critical illness insurance premium at a discounted group rate. The policy they buy then helps cover out-of-pocket expenses related to one illness or a number of illnesses, depending on the kind of policy they choose. Payments can go toward out-of-pocket medical costs, including co-pays and deductibles, and nonmedical expenses, such as transportation, household bills, and childcare.

For many, these policies seem like a good way to help manage rising healthcare expenses. The average annual premium that workers pay toward health insurance coverage for a single person, for example, has risen from about $3,600 a decade ago to more than $5,300 today, according to the Kaiser Family Foundation. At the same time, the average annual deductible for an individual has also climbed, up 49 percent over the last five years, from nearly $1,000 in 2011 to nearly $1,500 in 2016. That leaves consumers having to pay more if they become sick.

The relatively low premiums make critical illness insurance policies seem more attractive. A single, nonsmoking 50-year-old man who buys a $50,000 policy for a cancer-only plan—the highest coverage limit Humana One provides for these plans—would pay around $70 per month for a plan.

That might not sound too onerous, especially if the man is diagnosed with cancer. But if he is diagnosed with a different illness, the insurance won’t apply.

Besides that, critical illness insurance doesn’t offer the same protections that traditional health plans do under the Affordable Care Act, says Betsy Imholz, special projects director at Consumers Union, the policy and mobilization arm of Consumer Reports.

If you have a pre-existing condition, for example, a critical illness plan doesn’t have to cover it, but a traditional plan does. While both critical illness insurance and traditional insurance plans can charge higher premiums as you age, critical illness policies are more likely to do so than traditional plans. Some critical illness plans can even reduce or completely drop your benefits after you reach a certain age, when you might need the coverage the most.

For some, critical illness insurance provides peace of mind, which should not be discounted. But for many, critical illness insurance is rarely worth the money. “People greatly overestimate their risk of getting cancer at any one time compared to getting lots of other conditions that are less frightening but also very expensive,” Jost says.

If you’re concerned about your coverage, first check your traditional insurance to understand exactly what your benefits are if you’re faced with a serious medical condition. If you’re feeling vulnerable, during the upcoming open enrollment period, shop for a new insurance plan that offers lower out-of-pocket expenses. Your premium will likely be higher, but it might be worthwhile if you don’t need to purchase a critical illness policy to offset the difference.