# Peak Flow Log vs PRN Dose Timer

The clearest difference is update cadence: PRN Dose Timer at every 3 days against Peak Flow Log's every 5 weeks. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Peak Flow Log sells 1 one-off in-app purchase and PRN Dose Timer sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Peak Flow Log ships an update every 5 weeks, PRN Dose Timer every 3 days. Both last shipped on October 31, 2026.

## The numbers

| Metric | Peak Flow Log | PRN Dose Timer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.0 (1 ratings)](https://appshunter.io/ios/app/peak-flow-log-asthma-diary/id6794622470/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 5 weeks | **Every 3 days** |
| Monetization | Free with in-app purchases | — |
| Size | 2 MB | 0 MB |
| Requires iOS | 17.0 | 17.0 |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [Yoshifumi Sato](https://appshunter.io/developer/6780413827) | [keisuke haraguchi](https://appshunter.io/developer/6777524962) |

## What reviewers say

### Peak Flow Log

[App page](https://appshunter.io/ios/app/peak-flow-log-asthma-diary/id6794622470)

Record your peak flow readings and visualize your asthma zones. Log reliever puffs, symptoms, and triggers to track trends and generate PDF reports for your doctor. Your data stays private and works offline.

**Highlights:** Visualize asthma zones (Green, Yellow, Red), Log reliever puffs, symptoms, and triggers, Track trends over time, Create shareable PDF reports, Offline functionality, Multi-user support

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Peak Flow Log Pro | $3.99 | one-time |


### PRN Dose Timer

[App page](https://appshunter.io/ios/app/prn-dose-timer/id6799366426)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock | $1.99 | one-time |


## Frequently asked questions

### Is Peak Flow Log free?

Peak Flow Log is free to download, with in-app purchases available.

### Is PRN Dose Timer free?

PRN Dose Timer is free to download, with in-app purchases available.

### Do Peak Flow Log or PRN Dose Timer have ads?

Neither Peak Flow Log nor PRN Dose Timer shows ads.

### Which is updated more often, Peak Flow Log or PRN Dose Timer?

Peak Flow Log ships an update every 5 weeks, and PRN Dose Timer every 3 days. Most recently, Peak Flow Log was updated on October 31, 2026 and PRN Dose Timer on October 31, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*