Comparison

STI Tx Guide vs Diagnosaurus® DDx

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

STI Tx Guide

Provides healthcare professionals with up-to-date, evidence-based recommendations for the prevention, diagnosis, and treatment of sexually transmitted infections. Features include clinical care guidance, sexual history resources, and patient materials for effective patient management.

Highlights
  • STI prevention recommendations
  • Diagnosis guidance
  • Treatment protocols
  • Clinical care assistance
  • Sexual history resources
  • Patient management tools
Features
Read full description

The new app offers quick and easy access to streamlined STI prevention, diagnosis, and treatment recommendations. The user-friendly interface includes more clinical care guidance, sexual history resources, patient materials, and other features to assist with patient management. The STI Treatment (Tx) Guidelines mobile app serves as a quick reference guide for doctors and related parties on the identification of and treatment for sexually transmitted diseases (STDs). The full STI Treatment Guidelines (cdc.gov) can be accessed at https://www.cdc.gov/std/treatment-guidelines/default.htm. The guidelines provide current evidence-based prevention, diagnostic and treatment recommendations that replace the 2015 guidance. The recommendations are intended to be a source for clinical guidance. Healthcare providers should always assess patients based on their clinical circumstances and local burden. DISCLAIMER THE MATERIALS EMBODIED IN THIS SOFTWARE IS PROVIDED TO YOU "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE CENTERS FOR DISEASE CONTROL AND PREVENTION (CDC) OR THE UNITED STATES (U.S.) GOVERNMENT BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT, SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, LOSS OF PROFIT, LOSE OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD PARTIES, WHETHER OR NOT CDC OR THE U.S. GOVERNMENT HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.

About

Diagnosaurus® DDx

This medical reference tool assists healthcare professionals in performing differential diagnoses quickly and confidently. It offers a searchable database of over 1,000 diagnoses, cross-referenced for related conditions, and allows users to save favorite entries and make custom notes.

Highlights
  • Over 1,000 differential diagnoses
  • Search by organ system, symptom, or disease
  • See Related DDx feature
  • Save favorite entries
  • Highlight and make custom notes
  • Universal Index Search
Features
Read full description

** Top-Selling App Used by Tens of Thousands of Health Professionals, Worldwide ** ABOUT DIAGNOSAURUS DDX This quick-reference tool helps healthcare professionals perform differential diagnosis with speed and confidence at the point of care. With Diagnosaurus you can quickly search over 1,000 diagnoses by organ system, symptom, or disease, or you can view all entries. Use the valuable “See Related DDx” feature within each entry to consider alternative diagnoses and quickly link to those entries. The convenient “Favorites” feature allows you to save specific searches and bookmark in your personal archive. FEATURES • More than 1,000 differential diagnoses • Highlight and make custom notes within entries • Entries organized in quick-read format • “See Related DDx” links to other potential diagnoses • Disease, symptom, and organ system indexes • “Favorites” for bookmarking important entries • Universal Index Search to help find answers fast Author: Roni F. Zeiger, MD Publisher: McGraw-Hill Medical Powered by: Unbound Medicine

Screenshots

STI Tx Guide4 screens
Diagnosaurus® DDx4 screens

Verdict

The call

The clearest difference is rating: Diagnosaurus® DDx at 4.8 against STI Tx Guide's 3.5. Diagnosaurus® DDx also leads on ratings volume (2.5K vs 36) and review sentiment (53% vs 36%). STI Tx Guide's advantage is in-app purchases (none vs 1) and update cadence (every 2 months vs every 10 months). On price, ads and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Diagnosaurus® DDx sells 1 one-off in-app purchase. STI Tx Guide asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Diagnosaurus® DDx holds the better App Store score, 4.8 against 3.5. That said, the two scores are not equally well evidenced: Diagnosaurus® DDx has 2.5K ratings behind it against 36, so its average is the more settled of the two. Written reviews point the same way: 36% of STI Tx Guide's written reviews are positive against 53% of Diagnosaurus® DDx's.

UpkeepUpdate frequency

STI Tx Guide ships an update every 2 months, Diagnosaurus® DDx every 10 months. The most recent releases landed on October 23, 2026 and October 24, 2026 respectively.

Scorecard7 real differences · 3 level
STI Tx Guide versus Diagnosaurus® DDx: the parameters behind the verdict, then further details
ParameterSTI Tx GuideDiagnosaurus® DDx
PriceFreeFree
Rating3.5 (36 ratings)4.8 (2.5K ratings) — better
Positive reviews35.7% of reviews53.2% of reviews — better
Number of ratings362.5K — better
Update frequencyEvery 2 months — betterEvery 10 months
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPodiPhone, iPad, iPod, Mac — better
Requires iOS15.015.0
Further details — not scored
Size36 MB19 MB
Age rating12+17+
DeveloperCenters For Disease Control and PreventionUnbound Medicine, Inc.

Customer experience

STI Tx Guide

All ratings36 ratings
Positive63.9%
Neutral2.8%
Negative33.3%
Written reviews14 reviews
Positive35.7%
Neutral7.1%
Negative57.1%

Diagnosaurus® DDx

All ratings2,500 ratings
Positive96.2%
Neutral1.6%
Negative2.2%
Written reviews77 reviews
Positive53.2%
Neutral2.6%
Negative44.2%

Bugs and requests

STI Tx Guide

Not enough reviews yet to summarise bugs or requests.

Diagnosaurus® DDx

Reported bugs

3 issues
  • Subscription issues and inability to restore purchases
  • Blank pages and non-functional content
  • Compatibility issues with newer iOS versions

Requested features

5 requests
  • Add ability to edit or add custom differential diagnoses
  • Improve search functionality and navigation
  • Provide more detailed information on conditions
  • Integrate with other medical resources and databases
  • Improve support for older devices and iOS versions

In-app purchases

None

STI Tx Guide

No in-app purchases

1 purchases

Diagnosaurus® DDx

One-time1
  • Diagnosaurus DDx$4.99

Questions

Is STI Tx Guide free?
STI Tx Guide is free to download, with no in-app purchases.
Is Diagnosaurus® DDx free?
Diagnosaurus® DDx is free to download, with in-app purchases available.
Which has better reviews, STI Tx Guide or Diagnosaurus® DDx?
Diagnosaurus® DDx is rated higher. STI Tx Guide averages 3.5 out of 5 from 36 ratings, while Diagnosaurus® DDx averages 4.8 from 2.5K ratings.
Do STI Tx Guide or Diagnosaurus® DDx have ads?
Neither STI Tx Guide nor Diagnosaurus® DDx shows ads.
Which is updated more often, STI Tx Guide or Diagnosaurus® DDx?
STI Tx Guide ships an update every 2 months, and Diagnosaurus® DDx every 10 months. Most recently, STI Tx Guide was updated on October 23, 2026 and Diagnosaurus® DDx on October 24, 2026.

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