>> reporter: she's got to be fast. there's a lot of competition for human guinea pig these days. especially moms looking for extra cash. >> i did one study and thought, okay, that's like a lot of money in a short amount of time. >> reporter: jennifer says she can make up to $5,000 for one trial. she has tested allergy sprays to wearable medical devices. >> for a week that i did it, it was $1,000. >> reporter: she says it was uncomfortable but worth it to be able to stay home with her children. one trial she regrets the one that required needles. >> i won't do that again. >> reporter: it's not just the money that's attractive. for annette santana, participating in drug trials has dramatically improved her health. >> my sugars are stable. >> reporter: yvette had to once choose between food and medicine. now her diabetes drugs are paid for, saving her up to $500 a month. while most trials are considered