With therapists in high demand and long waiting lists that make it challenging to find a provider, using a mental health app might seem like a tempting and relatively inexpensive way to get help.

These apps claim to help with issues as varied as addiction, sleeplessness, anxiety and schizophrenia, often by using tools like games, therapy chatbots or mood-tracking diaries. But most are unregulated. Although some are considered useful and safe, others may have shaky (or nonexistent) privacy policies and a lack of high-quality research demonstrating that the apps live up to their marketing claims.

Stephen Schueller, the executive director of One Mind PsyberGuide, a nonprofit project that reviews mental health apps, said the lack of regulation has created a “Wild West,” that was exacerbated when the Food and Drug Administration loosened its requirements for digital psychiatry products in 2020.

It is difficult to pinpoint the exact number of mental health apps available, but one estimate from 2017 said there were at least 10,000 available for download. And these digital products are becoming a lucrative business. At the end of last year, Deloitte Global predicted that worldwide spending on mobile mental health applications would reach close to $500 million in 2022.

So how do you make an informed decision about whether to add one to your phone? We asked several experts for guidance.

Who might benefit from a mental health app?

In general, mental health apps can help people gain insights into how their thoughts, feelings and actions interact with each other, said Dr. John Torous, the director of the digital psychiatry division at Beth Israel Deaconess Medical Center. They can also help facilitate the skills that patients learn during therapy, he added.

Dr. Stephanie Collier, the director of education in the geriatric psychiatry division at McLean Hospital, noted that mental health apps “can work nicely alongside physical activity goals, such as step counters” because exercise can help reduce anxiety and depressive symptoms.

“Similarly,” she said, “apps that teach skills such as deep breathing can be helpful to anyone experiencing stress — whether stress is the result of an anxiety disorder or just circumstances.”

For some people, however, apps are not a great fit.

Apps work best when people are motivated and have mild illness, Dr. Collier said. “People with moderate or severe depression may not have sufficient motivation because of their illness to complete modules on a mobile app.”

Can mental health apps become a substitute for therapy?

No, and especially not if you have impairing symptoms.

“These are not stand-alone treatments,” Dr. Collier said. “But they can be effective when used in tandem with therapy.”

Ideally, mental health apps teach skills or provide education, said Vaile Wright, the senior director of health care innovation at the American Psychological Association.

“It could be this opening to thinking about ‘Maybe I should seek out some more professional help,’” she said.

Dr. Torous offers his patients a free app called MindLAMP, which he created to augment their mental health treatments. It tracks people’s sleep patterns, physical activities and changes in symptoms; it can also customize the “homework” that therapists give their patients.

Have these apps been screened by a regulatory agency?

For the most part, no. The Food and Drug Administration regulates a small subset of apps that provide treatment or diagnosis, or are associated with regulated medical devices. But most mental wellness apps are not subject to government oversight.

Thus, some apps make unsubstantiated marketing claims, experts warn, or even worse, offer inaccurate and potentially harmful information.

“The number of products far outstrips the research evidence that’s out there,” said Dr. Schueller, who is also a clinical psychologist and associate professor at the University of California, Irvine. “Unfortunately a lot of the research that exists in this area is done internally by companies,” he added, rather than unbiased outside groups.

In addition, there is no requirement that all wellness apps conform to the Health Insurance Portability and Accountability Act, known as HIPAA, which governs the privacy of a patient’s health records.

In a recent paper, Dr. Torous and his colleagues examined regulatory gaps in digital health apps, revealing various problems that could arise, such as inaccurate phone numbers for suicide crisis help lines. The paper also highlighted an earlier study that found 29 of the 36 top-ranked apps for depression and smoking cessation shared user data to Facebook or Google, but only 12 accurately disclosed this in their privacy policies.

And in March, a study concluded that an app created to help those with schizophrenia performed no better than a placebo (in this case, a digital countdown timer).

“All these apps claiming to be effective in early or preliminary or feasibility studies likely need to study themselves with higher quality science,” Dr. Torous said.

Lastly, just because an app is popular in the online marketplace doesn’t mean that it is going to be safer or more effective.

How do you go about choosing one?

“As a clinician who has used apps in care for well over five years, it was always tricky to understand what apps to match to patients,” Dr. Torous said. “You really have to think about how we can respect people’s individual backgrounds, preferences and needs.”

Instead of looking for the “best app,” or the one with the most ratings, try to make an informed decision about which app would be the best match for you, he added.

One place to start researching is the website Mind Apps, which was created by clinicians at Beth Israel Lahey Health in Massachusetts. It has reviewed more than 600 apps and is updated every six months. Reviewers look at factors like cost, security and privacy concerns and whether the app is supported by research.

Another website, One Mind PsyberGuide, evaluates health apps for credibility, user experience and transparency of privacy practices. The project, which is affiliated with the University of California, Irvine, has more than 200 apps in its database, and each is reviewed annually.

What should you look for in an app’s privacy policy?

Although MindApps and One Mind Psyberguide both present an overview of an app’s privacy policy, you may want to dig into the specifics yourself.

Look at what kinds of information it collects, its security measures and whether it sells information to third parties or uses information for advertisements, Dr. Collier said.

According to a 2019 study, fewer than half of mobile apps for depression even have a privacy policy, and most privacy policies are provided only after users enter their data.

“It’s no wonder that some people have reservations about using mobile apps like this when you don’t know if or how your data is being used,” said the lead author of the study, Kristen O’Loughlin, a graduate research assistant at the Virginia Commonwealth University School of Medicine.

Choose your app based on the information available and your own comfort level with disclosing personal information, she added.

Which apps are reputable?

The answer to this question may depend on whom you ask. But all of the experts spoke highly of the mental wellness apps developed by the federal government, like PTSD Coach; Mindfulness Coach; and CPT Coach, which is for people who are practicing cognitive processing therapy with a professional mental health care provider.

These apps are not only well studied but also free, with no hidden costs. They have excellent privacy policies and state that personal information will never be shared with a third party.

In addition to those apps, Dr. Collier recommends:

• Breathe2Relax (an app designed by an agency in the U.S. Department of Defense to teach belly breathing)

• Virtual Hope Box (an app produced by the Defense Health Agency that offers support in emotional regulation and stress reduction)

  For more suggestions, check out this list of apps on the University of California, San Francisco’s psychiatry and behavioral sciences department website. The list, which was created in consultation with Dr. Schueller, includes several free options.