Gayla George, 59, is being treated for breast cancer. She and her husband, Leroy, who live in Havre, Mont., have health insurance, thanks to her job as an elementary school paraprofessional. And yet, the costs are mounting.

George’s doctors prescribed a double mastectomy, followed by chemotherapy. Each of her many doctor’s appointments comes with hefty co-pays. She’s used up all her paid time off—she missed six weeks of work after her surgery—and every chemo treatment means another week off from work. “My last paycheck was for $3.38 for two weeks after they took off insurance and taxes,” she says.

Since there’s not much in the way of specialty medical care in her small town, George drives to the city of Great Falls—some 118 miles each way—for her surgeries and related care. In the winter, she often has to stay in Great Falls overnight rather than risk driving home over snowy or icy roads. 

So when a colleague heard about George’s struggles, she set up a GoFundMe campaign, hoping to raise $50,000.

The growth of crowdsourcing

George and her campaign are part of a growing number of GoFundMe pages devoted to raising money to help people pay medical bills.

Many who face outsize medical bills turn to family and close friends for help. But increasingly, those who can’t tap those sources—or whose needs exceed what they can raise—turn to acquaintances and even strangers.

Crowdfunding, in theory at least, makes sense: If enough people contribute even small amounts, no one party has to shoulder an enormous burden. An $1,000 bill, for example, could be covered if 100 people chip in just $10 each.

That’s propelled the growth of crowdfunding sites. In 2014, GoFundMe campaigns raised $46 million: last year, campaigns for medical expenses alone raised $650 million. Other crowdfunding sites have seen similar growth.

And a recent study by Nerdwallet found that an average of 41% of campaigns on crowdfunding websites including GoFundMe, as well as GiveForward, Red Basket, and Plumfund were for medical costs.

In an interview, GoFundMe CEO Rob Solomon said that the company didn’t anticipate that medical funding would become such a big part of the site, but that by default, it’s become an “indispensable institution.”

Why we’re turning to strangers

Some who struggle to manage medical costs lack insurance, of course. But many others, like George, are insured. Their deductibles and out-of-network charges often translate to big bills. “Millions of people have such high out-of-pocket costs for copays and deductibles that they are effectively underinsured,” says Sara Collins, a healthcare economist at the Commonwealth Fund.

A recent study found that an average of 41% of campaigns on crowdfunding websites were for medical costs.

A recent survey from the nonprofit Commonweath Fund found that 46% of people said they would not be able to cover a $1,000 medical bill in 30 days. People age 45 and older in high-deductible plans are more at risk of delaying the care they need, skipping doses of a prescription to make it last longer, and not seeking specialty follow-up care, says Collins.

And then there are emergencies. Another study found that Americans borrowed $6.12 billion just to pay for medical emergencies—not illnesses or conditions—in 2017. 

Auxiliary costs hurt too, says Brent Neiser, senior director at the National Endowment for Financial Education: Missing work, travel, and paying for medical equipment that isn’t covered by insurance.

Don’t get left empty-handed

While GoFundMe and other sites have helped some people out of a jam, many others are left disappointed. On average, just over 1 in 10 medical and health care campaigns are fully funded, NerdWallet found.

According to NerdWallet, campaigns that are set up by friends or family members on behalf of the person in need tend to attract more funds than those started by those who need the money for themselves.

Sharing the campaign on social media also increases the odds, NerdWallet says.

Looking to donate? Some articles have noted that consumers should be on the lookout for potential scams (GoFundMe notes that its campaigns are backed by a guarantee policy that insures funds are returned to the donors if they aren’t used for the cause intended). It’s also good to check exactly how the money is being used: According to a recent study, crowdsourcing funds are often raised to cover experimental or non-doctor-recommended treatments.