Actress Dawn Wells, homespun Mary Ann on the 1960’s sitcom Gilligan’s Island, lost a lot of money in the 2008 financial crisis — a setback compounded this year when she broke her knee in an accident and underwent an expensive surgery. The resulting medical bills left the 79-year-old actress financially strapped. Fortunately, fans rallied to her aid with an online campaign that raised money to pay her medical debt.

A major medical expense can occur without warning, even straining the financial resources of people who don’t already have money troubles — and few of us can rely on a fanbase to help us out. Consider the case of Crystal Roberts, who in 2015 was transported to a hospital in Texas for three hours of lab tests and x-rays following a minor car accident. Because she was uninsured, the hospital charged Crystal full price: $11,037.35. (She sued, arguing that the charges were unreasonable — and won.)

According to a 2016 study from the Kaiser Family Foundation, medical debt is an equal-opportunity destroyer, hitting not only the uninsured but the insured as well. It also affects people across the financial spectrum, from low-income to upper-income.