Is Flo safe and private to use?

Yes, largely. Flo is a different product on privacy today than the one a 2019 investigation exposed, and most of what changed since is independently checkable, not just claimed. That does not erase what happened, and it does not answer whether Flo is the right tracker for you religiously. It only answers whether it currently handles your data responsibly. Here is exactly what happened, what it cost Flo, what changed afterward, and how to check any of this yourself instead of taking an app's word for it.

• The 2019 report and the 2021 FTC order. A Wall Street Journal investigation in February 2019 found that Flo was sending data to Facebook, Google and other analytics firms as "app events," including the fact that a user was pregnant, despite telling users their health information would stay private. The U.S. Federal Trade Commission investigated and finalized an order in June 2021 requiring Flo to get users' affirmative consent before sharing health information with anyone else, to instruct every third party that had received that data to destroy it, and to undergo an independent review of its privacy practices going forward.
• The 2025 class action settlement, a separate case over the same conduct. Users who logged menstruation or pregnancy information in Flo between November 2016 and February 2019 were covered by a lawsuit that ran alongside the FTC case. Flo agreed to pay $8 million and Google a further $48 million to settle it in 2025, on top of a $3.5 million settlement the analytics firm Flurry had already paid for its part, putting the total across all three companies at $59.5 million. Google settled without admitting liability; Flo's settlement came in the middle of trial.

What changed is not just a promise. An outside firm, Guidepost Solutions, audited Flo's privacy practices as part of the FTC settlement and reported in March 2022 that it found no gap between what Flo's privacy policy said and what the app actually did. In September 2022, in the weeks after Roe v Wade was overturned, Flo launched Anonymous Mode, which strips your name, email and technical identifiers from your account so a legal request tied to your identity has nothing in Flo's own records to connect to your cycle data. In January 2024 Flo says it became the first period tracker to earn ISO 27701 certification, the international standard for privacy information management, alongside the ISO 27001 security certification most large health apps hold; both require an accredited outside auditor, not just Flo's own testing, and the company says its most recent audit, completed in August 2026, returned no findings. Separately from anything Flo has said about itself, the Mozilla Foundation tested Flo directly in 2026 rather than relying on its marketing and scored it 7 out of 10, ahead of most trackers it reviewed, finding no evidence that Flo currently shares your logged symptoms or cycle classifications with outside advertisers.

None of that undoes 2016 to 2019. The FTC's order made Flo tell Facebook, Google and its other recipients to delete what they had, it did not make the original sharing not have happened, and there is no independent way to confirm every recipient actually complied. A certification is also a snapshot of what a company's systems do today, scoped to whatever the auditor was asked to check, not a permanent guarantee, which is exactly why it is worth confirming that any tracker, Flo included, still points to a current audit rather than one from years ago. And like most period tracker privacy policies, Flo's still allows it to hand data over to comply with a valid legal demand; Anonymous Mode limits what there is to hand over, it does not remove that clause.

None of this touches the question a Muslim woman is usually actually asking when she looks at Flo. It still has no idea what hayd, istihadah or nifas are, so it cannot tell you whether a day of bleeding counts toward a missed prayer or fast; see how the best Flo alternative for Muslim women actually compares on both privacy and that religious gap.

Whatever tracker you are checking, Flo or otherwise, the same short list applies:

• Does it point to an audit or certification you can verify, or only to its own privacy page? An ISO certificate or a named audit firm can be checked independently; "we take your privacy seriously" cannot.
• Has an outside reviewer tested it recently, not years ago? Our answer on the best tracker for privacy covers this checklist in full.
• What does it say it will do with a legal demand for your data? The real question is how much it holds to hand over in the first place, not whether the clause exists.
• Can you use it without your name attached, and can you delete what you logged?

If what you are actually deciding is which tracker to use as a Muslim woman rather than whether Flo specifically is safe, what actually separates a tracker built for hayd, istihadah and nifas from a general calendar app covers the full list, including where Nisaa sits on it: it does not sell your data, keeps your health information out of the app's own ad and analytics tools, and is on the App Store.