A new NHS app which will help patients book GP consultations "cannot create appointments out of nowhere", leading doctors have said.
The app has been hailed by Health and Social Care Secretary Jeremy Hunt as the "death knell of the 8am scramble for GP appointments".
Patients will be able to book appointments, look at their records, order repeat prescriptions and access 111 online for urgent medical queries.
The app will also allow patients to address longer-term concerns such as setting out their end of life care and organ donation preferences.
But the British Medical Association (BMA) said that while the app has potential, the Government must address the "workforce crisis" within general practice.
At present there are not enough GPs to meet rising demand, the BMA said.
Launching the app, Mr Hunt said: "The NHS app is a world first which will put patients firmly in the driving seat and revolutionise the way we access health services.
"I want this innovation to mark the death knell of the 8am scramble for GP appointments that infuriates so many patients.
"Technology has transformed everyday life when it comes to banking, travel and shopping.
"Health matters much more to all of us, and the prize of that same digital revolution in healthcare isn't just convenience but lives improved, extended and saved."
Dr Richard Vautrey, chairman of the BMA's GP committee, said: "GPs understand and share the public's frustration at not always being able to get an appointment, and this app has the potential to offer patients who are comfortable using this type of technology another option to contact their practice.
"In using this it is important to ensure patient confidentiality is protected and develop systems that enable patients are directed to the right course of action or appointment for their condition.
"If developed and tested appropriately, it could also be helpful for those ordering repeat prescriptions or receiving test results.
"However, it cannot create appointments out of nowhere. One of the fundamental problems facing general practice is that there are not enough GPs to meet rising demand, meaning patients wait longer and doctors face unmanageable workloads.
"So, while innovation such as this app has potential, the Government's priority must be to address the workforce crisis."
Earlier, the chairwoman of the Royal College of GPs warned that nearly every GP surgery in England is short of a family doctor.
Professor Helen Stokes-Lampard said there is a "crisis" in the GP workforce.
In an interview with the Press Association, she said that many doctors are so overwhelmed with workload pressures that they feel they are "not providing a safe enough service".
Testing of the new app, which will be available for patients in England, begins in September and it is expected to be ready to download from the App Store or Google Play in December.
Sarah Wilkinson, chief executive of NHS Digital, said: "We are working hard to deliver the Secretary of State's vision for an NHS app which provides much easier access for individuals to key NHS services.
"I have no doubt that people will hugely welcome the ability to access self-help diagnostic tools, more easily book GP appointments, view test results and order repeat prescriptions, and tell us about their personal preferences with respect to organ donation, use of their data and other aspects of their care.
"We all know that demand for precious NHS services is escalating, and for a large portion of the population digital channels are a preferred means of access to data and services, so this is an opportunity to provide the easier access people want and relieve some burden from frontline providers."
It comes as the NHS marks its 70th anniversary this week.
Matthew Swindells, NHS England national director of operations and information, said the app would allow patients to take charge of their own healthcare.
He added: "The new app will put the NHS into the pocket of everyone in England, but it is just one step on the journey, we are also developing an NHS Apps Library and putting free NHS Wi-Fi in GP surgeries and hospitals."