Personal health is becoming increasingly mobile, and there are now thousands of apps aiming to address everything from lifestyle issues to chronic diseases. But can you trust these apps, the same way you trust your prescribed drugs and medical devices? Medical devices are generally regulated by the U.S. Food and Drug Administration, and although the FDA reviews some apps, experts say the agency's power and efforts aren't nearly enough to cover the 97,000 and counting health apps out there that are transforming consumer health.

"The FDA is woefully understaffed and under-resourced to oversee these things, particularly given the number of the thousands of apps that are [most likely] under FDA's jurisdiction," said health law expert Nathan Cortez, an associate professor of law at Southern Methodist University Dedman School of Law in Dallas, Texas. [9 Odd Ways Your Tech Devices May Injure You]

In an editorial published in The New England Journal of Medicine on Thursday (July 24), Cortez and his colleagues argued that health and medical apps hold the promise of improving health, reducing medical errors, avoiding costly interventions, and broadening access to care. But to reach their potential, these products have to be safe and effective, they said.

A large number of health apps, such as those that help you track your exercise or the calories in your meals, likely don't pose a concerning risk to consumers. But in more ambitious apps, such as an app to manage insulin doses for diabetic patients, any mistake, bug or misinformation could simultaneously affect thousands of patients, and emerging evidence reveals many products do not work as claimed, or the products make mistakes.

"Early studies evaluating whether these apps work or not tend to paint a pretty dim picture of them. The results aren't that promising," Cortez told Live Science.

Which apps need to be regulated?

In September 2013, the FDA gave its position on what types of products and technologies would fall under its jurisdiction. Currently, the agency has a pre-market review process for some apps, meaning that the app developer submits information to the agency to get the FDA's blessing, Cortez said. The agency also sometimes takes enforcement actions by issuing a public reprimand to a company if its products violate FDA's rules and regulations.

So far, the FDA has cleared about 100 medical apps over the past decade, with about 40 of these approvals coming in the past two years, according to the agency. These apps are mobile forms of traditional medical devices, or are accessories to a regulated medical device. For example, one app evaluated lets physicians see data from electrocardiograms, and another offers medication reminders and connects patients with their doctors.

Still, the FDA's jurisdiction is limited, and the line between what constitutes a medical app and what is just about health and fitness could be blurry, which is frustrating for developers, Cortez said.

Although a number of laws have been proposed in Congress that aim to change the FDA's regulatory approaches, none have passed so far. One of the main arguments against expanding the FDA's oversight is that too much regulation would stifle innovation in the mobile health industry.

But Cortez said that this common refrain is shortsighted. "If you let these apps proliferate without any real oversight or any real enforcement, I think you risk consumer confidence in these products becoming really low," he said. "If the majority of apps don't work, and make claims that aren't substantiated, I think that will undermine the market in the long run."

Clear and decisive rules by the FDA could help mobile health technologies mature into the next generation that actually fulfill all the promises that the industry has for these products, Cortez said.

"It looks like Congress is building momentum towards some kind of legislation, some type of bill actually passing," Cortez said. If Congress does pass a bill, it should give the FDA more resources and push the agency to provide clear, binding rules for these products, he said. "I think that'll help the industry in the long term."

Should you trust the medical apps on your phone?

Mobile health and medical technology apps are still in the early stages, but for every few hundred that don't do anything, there are several apps that are actually helpful.

People who would like a useful app for their health condition should make sure that the app is reputable, has been updated and doesn't have bugs. They should also keep an eye out for recalls and look for FDA-cleared apps, Cortez said.

"For example, if I had diabetes, and I was looking to use an app, I would definitely try to use one that the FDA has cleared in pre-market review process over one that hasn't been cleared," Cortez said.

However, Cortez noted that even though the products may have gone through the FDA's clearance process, they haven't been tested as rigorously as new drugs and medical devices.

"I would also make sure my doctor knew what I was doing," Cortez said. "It would be a joint decision with the doctor."

Email Bahar Gholipour. Follow Live Science @livescience, Facebook & Google+. Originally published on Live Science.