Plans to extend the Individual Health Record in Wales have been approved by health minister Edwina Hart.
This follows a successful pilot with the out-of-hours GP service and medical admissions unit in Gwent.
The £4.7m Assembly Government-funded scheme allows doctors, nurses and pharmacists to view, with the patient's permission, a copy of the information on their medical record, held by their GP.
Initially, the information will be shared between local GP surgeries and local unscheduled care providers. This Individual Health Record includes details of the patient's current medication and conditions, major health conditions, allergies, immunisations or vaccinations as well as blood pressure and test results.
An evaluation of the pilot found that clinicians using this information find the Individual Health Record invaluable in helping them make an informed decision on how to treat their patient. This is particularly helpful for older patients and those with long-term conditions.
Mrs Hart said: "Currently staff spend a lot of time taking medical histories and if they are in doubt about the course of treatment, patients are more likely to be admitted for further investigation. The absence of basic, but vital information, on medical histories or allergies, could have a detrimental impact on patient care and is a poor use of finite NHS resources.
"This system has already proved successful in Gwent, and I am keen for patients and staff across Wales to benefit from this as soon as possible. Using the electronic Individual Health Record clinicians will quickly have access to patient information and, in some cases, this could make the difference between life and death."
The Chief Medical Officer for Wales, Dr Tony Jewell, added: "Generally when patients present themselves to accident and emergency departments or to the GPs out-of-hours service, they may not be in a position to give all the details about their medication history clearly.
"This system will enable clinicians, at the touch of a button, be able to access information on the patient's health [so] they will be aware of their current medication or anything that may cause complications in their treatment. All of this information can be considered in providing the best care for patients."