'Lets Talk Clots' was developed by staff from Oxford University Hospitals NHS Foundation Trust in collaboration with the charity Thrombosis UK.
The app will feature in the discharge paperwork of patients with plans to incorporate it into admission paperwork as well.
The hospital admission period and the time after discharge may see patients at risk of developing a blood clot.
Symptoms such as new redness, pain or swelling in legs, difficulty breathing, fainting, coughing up blood or experiencing chest pain need immediate attention as these could indicate the development of a blood clot.
Venous Thromboembolism (VTE) prevention nurse at Oxford University Hospitals, Sarah Havord, came up with the idea for the app.
She said: "This resource is very much needed, providing free access to medically-approved information across the blood clot journey and, I believe, will help to save lives and restore lives affected by blood clots.
"I have been overwhelmed by the amount of support and help provided - it really wouldn’t have been possible without all those involved."
The app is now available for download on the Apple Store and Google Play.
For additional information, emails can be sent to [email protected].
Thrombosis UK is also promoting 'Let's Talk Clots' through postcards and posters displayed across hospital sites in Oxford and Banbury.