# ClinicalKey vs Primum

The clearest difference is review sentiment: Primum at 100% against ClinicalKey's 9%. Primum also leads on monetization model (ad-supported vs subscription). ClinicalKey's advantage is ads (none vs shown). On price, update cadence, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ClinicalKey ships an update every 5 weeks, Primum every 2 months. The most recent releases landed on September 14, 2026 and August 4, 2026 respectively.

## The numbers

| Metric | ClinicalKey | Primum |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.2 (5 ratings)](https://appshunter.io/ios/app/primum/id6651755259/reviews)** |
| Number of ratings | — | **5** |
| Positive reviews | 8.8% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | **Every 5 weeks** | Every 2 months |
| Monetization | Subscription | **Ad-supported** |
| Size | 55 MB | 53 MB |
| Requires iOS | **15.0** | 15.1 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 12+ | 17+ |
| Developer | [Elsevier Inc.](https://appshunter.io/developer/367031326) | [PRIMUM HEALTH, INC.](https://appshunter.io/developer/1707581637) |

## What reviewers say

### ClinicalKey

[App page](https://appshunter.io/ios/app/clinicalkey/id1041998175)

This app provides medical professionals with instant access to a vast library of clinical knowledge, including synoptic content and in-depth reference materials. It helps users stay updated on medical advancements, confirm diagnoses, and advance their research skills, all while offering CME/MOC/CE credits.

**Highlights:** Access to 30+ medical specialties, Synoptic content for quick answers, Full-text reference books and journals, Mobile-optimized medical calculators, Earn CME/MOC/CE credits, Intuitive search functionality

**In-app purchases:** none

**What reviewers like**

- 📚 High-quality, evidence-based clinical content
- 🎯 Intuitive interface and quick reference format
- 🔍 Similar functionality to website version
- 👍 Browse feature restoration appreciated by users

**What reviewers complain about**

- 🔓 Constant forced logout issues
- 🔐 Institutional login authentication failures
- ⏳ App freezes and perpetual loading screens
- 🚫 Missing textbook access in app vs website
- 📵 Frequent crashes and force closures

**Reported bugs**

- App stuck on loading screen after initial login
- Forced logout when closing or minimizing app
- Institutional login not working despite web access
- App crashes during search queries
- OpenAthens authentication failures

**Requested features**

- PDF download capability within the app
- Favorite/bookmark textbooks and articles
- Landscape mode support for iPad
- Find-on-page text search function
- Automatic session persistence and page memory


### Primum

[App page](https://appshunter.io/ios/app/primum/id6651755259)

Connect with expert oncologists for case-specific advice and treatment decision support. This app facilitates direct messaging with specialists, offering actionable insights and a platform to manage your inquiries efficiently.

**Highlights:** Search and filter expert oncologists, Direct messaging with specialists, Real-time chat and notifications, Case-specific advice, Inbox management, Reference past inquiries

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is ClinicalKey free?

ClinicalKey is free to download, with no in-app purchases.

### Is Primum free?

Primum is free to download, with no in-app purchases.

### Do ClinicalKey or Primum have ads?

Primum shows ads; ClinicalKey does not.

### Which is updated more often, ClinicalKey or Primum?

ClinicalKey ships an update every 5 weeks, and Primum every 2 months. Most recently, ClinicalKey was updated on September 14, 2026 and Primum on August 4, 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.*