Cycle-synced medications

Most reminder apps can only repeat on a calendar. If what you take depends on where you are in your cycle, that is the wrong clock.

How it works

Pick a medication and bind it to cycle days or a phase instead of a fixed date — iron on the first days of a period, magnesium through the luteal phase, a painkiller a couple of days before PMS is due. The schedule then moves with the cycle, and the reminders move with it.

Who this is for

People with a cyclical prescription — PCOS and endometriosis routines, cyclical hormone therapy — and anyone timing supplements to a phase rather than a date. No other reminder app binds arbitrary medications to a cycle, and cycle apps only remind for their own pill.

Predictions that admit what they don't know

The cycle prediction is explainable rather than a black box: it widens its window when your data is thin and stays quiet when there is not enough of it, instead of inventing a confident date. Logging a period corrects it immediately.

The most sensitive data gets the same architecture

Cycle data lives on your device like everything else. No advertising SDKs, no location or region requirement, nothing sold — the failures that produced this category's largest privacy penalties are not possible in a design that does not centralise the data for advertising.

FlowByFlow is not a contraceptive and does not provide medical advice or diagnosis. Cycle predictions are informational only — talk to your clinician about what you take and when.