# Smith's Patient Interview, 4/E vs Derm DDx

The clearest difference is price: Derm DDx at Free against Smith's Patient Interview, 4/E's $59.99. Derm DDx also leads on update cadence (every 5 months vs every 30 months). Smith's Patient Interview, 4/E's advantage is in-app purchases (none vs 1) and iOS requirement (10.0 vs 15.0). On ads and device support there is nothing between them.

Derm DDx is free to download; Smith's Patient Interview, 4/E costs $59.99 up front. Derm DDx sells 1 one-off in-app purchase. Smith's Patient Interview, 4/E asks for nothing beyond the download.

Smith's Patient Interview, 4/E ships an update every 30 months, Derm DDx every 5 months. The most recent releases landed on December 28, 2025 and October 17, 2026 respectively.

## The numbers

| Metric | Smith's Patient Interview, 4/E | Derm DDx |
| --- | --- | --- |
| Price | $59.99 | **Free** |
| Rating | — | **[4.3 (6 ratings)](https://appshunter.io/ios/app/derm-ddx/id6499524221/reviews)** |
| Number of ratings | — | **6** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 30 months | **Every 5 months** |
| Monetization | — | Free with in-app purchases |
| Size | 24 MB | 10 MB |
| Requires iOS | **10.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 17+ | 17+ |
| Developer | [Usatine & Erickson Media LLC](https://appshunter.io/developer/1466894388) | [Unbound Medicine, Inc.](https://appshunter.io/developer/300420400) |

## What reviewers say

### Smith's Patient Interview, 4/E

[App page](https://appshunter.io/ios/app/smiths-patient-interview-4e/id1455609444)

**Features:** macOS Compatibility

**In-app purchases:** none


### Derm DDx

[App page](https://appshunter.io/ios/app/derm-ddx/id6499524221)

This app provides visual, point-of-care guidance for diagnosing skin disorders. It features a large database of high-resolution images, allowing users to compare variations, zoom in, and access clinical history and treatment options for over 160 dermatologic conditions.

**Highlights:** 650+ high-quality dermatology images, Guidance for 160+ dermatologic conditions, Side-by-side image variations, Zoomable high-resolution images, Clinical history and treatment options, Cross-referencing to differential diagnoses, Full text search and custom notes

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Dermatology DDx | $69.99 | one-time |


## Frequently asked questions

### Is Smith's Patient Interview, 4/E free?

Smith's Patient Interview, 4/E costs $59.99, with no in-app purchases.

### Is Derm DDx free?

Derm DDx is free to download, with in-app purchases available.

### Do Smith's Patient Interview, 4/E or Derm DDx have ads?

Neither Smith's Patient Interview, 4/E nor Derm DDx shows ads.

### Which is updated more often, Smith's Patient Interview, 4/E or Derm DDx?

Smith's Patient Interview, 4/E ships an update every 30 months, and Derm DDx every 5 months. Most recently, Smith's Patient Interview, 4/E was updated on December 28, 2025 and Derm DDx on October 17, 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.*