Doctors who email patients instead of meeting with them in person or telephoning them could miss out on vital signs about a patient's ailments, according to an article in a leading medical journal.
The Department of Health has ploughed millions into pilot schemes assessing the effectiveness of e-consultations - such as over Skype or email.
But some medics have raised concerns about the prospect of emailing patients.
In an article published on thebmj.com, Emma Richards, academic GP registrar and honorary clinical research fellow at Imperial College London said that as well as the possibility of doctors missing out on emotional and clinical clues from patients, email communication could isolate elderly or poor patients who do not have access to the internet.
She argued that misunderstandings through emails could lead to blunders.
Meanwhile patients could become seriously unwell while waiting for an email to be answered, she said.
Dr Richards wrote that there is "no clear evidence" that that email communication improves access or saves money and that doctors were concerned that responding to emails would divert resources away from face-to-face consultations.
"Consultations using telephone or email share many characteristics, but telephone consultations offer emotional cues, such as tone of voice, as well as clinical clues, such as a wheeze," she wrote.
"Telephone facilitates two-way discussion in real time, to gather information, ask and answer questions, and check understanding. None of this can be done with a single email.
"Those in the greatest need of healthcare, such as elderly or infirm patients, may struggle to engage with email because of a lack of facilities or knowhow. Similar barriers exist for ethnic minorities and poor people, potentially creating a 'digital divide' of widening health inequalities."
She added: "The idea that patients can email unlimited requests and questions fills many GPs with dread -not only in terms of time but also clinical safety. Without immediate triage, what happens to the suicidal patient who sends an email on Friday night that goes unread until Monday, or the patient with chest pain who thinks she's dealt with the problem because she has emailed her doctor, who is on holiday?"
Dr Richards concluded: "Given the complexities of using email and understandable caution among GPs, it seems premature to be insisting that patients can have email communication with GPs. The Department of Health should first issue clear guidance on what can safely and appropriately be communicated by email and what resources are needed."
But arguing in favour of the move, Elinor Gunning, a locum family doctor in London and a clinical teaching fellow at University College London Medical School, said that email communication has the potential to improve convenience and efficiency for both patients and clinicians.
She said that well planned email services can provide an effective way of managing those with routine conditions.
It can also promote the doctor patient relationship though continuity of care, she argued.
While she admitted that some groups would be unable to use the method of communication she said it will be beneficial to others.
"Email services might facilitate access for those patients less able to use traditional methods of communication , such as housebound patients, those with hearing difficulties or younger patients who may be more likely to engage with this modern approach," wrote Dr Gunning.
"Admittedly some patient groups will be unable to benefit from email services. However, this is not a reason to deny this form of access to other patients."
She added: " The flavour of current UK health policy suggests that email use will soon be inevitable. If we do not engage with email now, implementation without our input may mean that GPs miss out on a vital opportunity to shape it's use, to the detriment of patients and clinicians."
An NHS England spokesman said: "There is real potential to make better use of technology like email and Skype in healthcare and there are many examples where it is already being used to good effect.
"Clearly using email won't be appropriate or possible in every situation and it should be used as a complement to face-to-face care. Security is also absolutely essential and services have the same duty of patient confidentiality as with traditional methods of communication."