England's chief medical officer has urged junior doctors to consider their "professional responsibilities" before their next strike.
Professor Dame Sally Davies said medics should also think about patients before a full stoppage over their dispute with the Government.
Dame Sally said the move was a "drastic step" that would "inevitably lead to patients suffering".
The first full walkout in the history of the NHS by junior doctors is planned for the end of the month, when they will withdraw all labour and provide no emergency cover.
Dame Sally said: "As a doctor, I can understand the anger and frustration felt by many junior doctors at this time. Junior doctors are the backbone of the NHS, working long and anti-social hours for their patients.
"But the withdrawal of emergency cover will inevitably lead to patients suffering, and sadly has the potential to bring far more serious consequences.
"I recognise that training now is very different from when I went through it, but I urge every junior doctor to consider their patients and their professional responsibilities before taking such a drastic step."
Last week saw the fourth stoppage in the dispute, with almost 25,000 procedures cancelled overall since the industrial action began.
In previous strikes, junior doctors provided emergency care cover, but strikes planned for April 26 and 27 will see the full withdrawal of labour by junior doctors - everyone up to consultant level - between the hours of 8am and 5pm.
Junior doctors are objecting to a new contract the Government says will create a truly seven-day service.
The major sticking point has been over weekend pay and whether Saturdays should attract extra unsocial hours payments.
Currently, 7pm to 7am Monday to Friday and the whole of Saturday and Sunday attract a premium rate of pay for junior doctors. But the Government has said the Saturday day shift must be paid at a normal rate.
The British Medical Association (BMA) also objects to other terms in the contract, which is due to be imposed from August, and has called on the Government to resume negotiations.
Acas has said it is ''ready to help'' if junior doctors and the Government want to use the independent conciliation service to try to resolve the dispute.
A BMA spokeswoman said: "The decision to take action like this is not something that junior doctors have taken lightly.
"The new contract is not only unfair for junior doctors but will damage the delivery of patient care in the long term.
"By sticking its head in the sand and ignoring the concerns of junior doctors, patient groups, MPs, medical colleges, members of the public, and senior NHS managers, the Government has left us with no choice.
"We deeply regret disruption to patients, but senior hospital doctors, GPs and other NHS staff will continue to provide emergency care on the days of action.
"We never wanted it to reach this point. So our message to the Government is clear, any future action is wholly avoidable. Lift the imposition and end this dispute through talks."