The first part of the junior doctors strike is set to begin on Tuesday, with medics protesting new contracts put forward by Health Secretary Jeremy Hunt.
The government has offered an 11% rise in basic pay for junior doctors, to offset a cut to the number of hours on a weekend for which junior doctors can claim extra pay for unsocial hours.
But junior doctors argue that the contracts, which the government says are needed to provide more seven-day services, will result in overworked staff who are in danger of making mistakes and putting patients' lives at risk.
Many also argue that, if imposed, the new conditions will drive many doctors to look abroad for employment.
The first strike, which will last for 24 hours from 8am on 12 January, will affect nearly 4,000 operations, according to NHS England.
Hunt has said the strike could see A&E departments forced to close on the day, putting patients at risk, and has urged doctors to reconsider before "rushing to the barricades".
"Frankly it is the busiest time of the year for hospitals right now. The last thing I want to be doing is diverting precious management resource into trying to assess how they will keep their patients safe if junior doctors don't turn up for work. It is a very, very serious thing," he told the Telegraph earlier this week.
David Cameron on Monday also pleaded with junior doctors to call off their "damaging" strike, saying it will cause "real difficulties" for patients and "potentially worse".
The Prime Minister urged medics "at this late stage" to get back around the table before the proposed walkout.
He said: "This strike is not necessary, it will be damaging.
"We are doing everything we can to mitigate its effects but you can't have a strike on this scale in our NHS without there being some real difficulties for patients and potentially worse."
But here, eight junior doctors explain to the Huffington Post UK why they feel driven to take action.
"I became a doctor to help people. Simple, predictable but totally true and I am not alone in this sentiment. The NHS is currently propped up by those who are dedicated to helping the public. However, Mr Hunt seems to have taken this sense of vocation as a sign of weakness and is intent on demoralising a workforce that is already on its knees.
"Working in A&E, I know better than most the impact that a junior doctor strike could have on the public. So why would a profession, which is driven by its duty to its patients, seemingly discard this in order to strike?
"Well, in my opinion, we have no choice. The risks of not striking are so much worse. I truly believe that it is better to have a planned withdrawal of services, on isolated occasions, than let Mr. Hunt proceed with his proposed contract which, I have no doubt, will see a move towards privatisation.
"So, its with a heavy heart, that I will quiet my fears about striking because, for all my future patients, the withdrawal of care might not be so temporary."
"I am striking because I feel so overworked currently.
"With the new contract they are removing current hour restrictions meaning they deem it appropriate for me to work an average of 60 hours a week but my hospital can rota me for up to 72 hours before being fined. Currently the maximum is 48."
Junior doctors on strike at Lancashire's Tameside Hospital
"Firstly, it's not about the money. It's really not. It's about the hours. We currently do up to 13 hour shifts (paid - forget the voluntary overtime because an arrest call went out during hand over or you urgently need to refer a patient for further specialist treatment after your shift has ended). For 13 hour shifts we have to be on the ball throughout, if not you become reliant on somebody else (who is also on a 13 hour shift) to catch your mistakes and make sure best care is provided. Usually, this works fine and we manage.
"By taking away the caps on the number of hours we work patient safety WILL be put at risk. It is inevitable. I don't want my gran being treated by a junior doctor (just to highlight - working in hospitals you are a junior doctor right up until you are a consultant) at the end of a 90+ hour week.
"Jeremy Hunt co-authored a book advocating the denationalisation of the NHS and taking up an American style government. By using forward these plans he is one huge leap closer in that dream of his. Who wins in that scenario?
"Well...I don't know if working in a system you don't believe in is winning, but financially - it will be doctors who are better off. We will get paid significantly more than we do now. But we don't want that. What we want in an NHS that is equal and accessible to all. A system that we believe in.
"It was in the news today that many GP practices are having to stop taking on extra patients because GP staffing levels are low and it is currently difficult to recruit. It was also in the news that a number of medical students were now reconsidering their choice of subject. If these proposals go through many of my friends and colleagues are also strongly considering working in a system abroad - one where they feel more satisfaction, value, feel they are able to work in a safer environment where they are less liable to make mistakes."
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"To me, being a doctor has never felt like a job it's been something that gets me up in the morning and inspires me on a daily basis. The teams that I've worked with in the NHS have been some of the best, most selfless people I've met to date and I've learnt more about myself in the six months I've qualified than I could have imagined.
"The necessity to strike, for me, is because I cannot let Jeremy Hunt stretch such an incredible workforce that has provided me and I know many others, with the sentiments I've just shared.
"A tired, demoralised and undervalued feeling workforce won't be good for patient care and it won't be good for us.
"I want to inspire more people to work in this profession and I want to maintain my genuine enthusiasm and love for the 'job'. Don't take that away from me, Jeremy."
"Striking is an absolute last resort and the government should be deeply ashamed that NHS staff have been pushed so far into a corner that they are forced to use it as their only means of communication.
"The NHS workforce would love to work with the government to build a better NHS through proper planning and funding; improving the service we are able to offer every single one of the seven days we already work. But no more cuts and no more unilateral imposition. There is no weekend effect. No more lies.
"Start listening. Start caring for patients."
"I'm striking for our patients, who deserve safe, free healthcare from cradle to grave.
"I'm striking for my colleagues, who have been in this profession far longer than I and are at breaking point from being undermined and undervalued.
"I'm striking for today's and tomorrow's doctors who deserve fair pay and safe working hours. I'm striking to preserve the future of our NHS."
"I feel undervalued by the government's manipulation of statistics and pressuring, for example when Bruce Keogh put out a statement about terrorist attacks [Keogh was accused of twisting the case against junior doctors after writing a letter to the BMA questioning whether striking junior doctors would be available to help in the event of a Paris-style terror attack].
"The government is unwilling to negotiate."
Health secretary Jeremy Hunt
"Striking to me is no longer just an hours issue, or a money issue. I think for a lot of doctors it goes far deeper than that. We're seeing the NHS break before our very eyes and feeling absolutely powerless to do anything about it.
"My current rota is only half full. That means the other half is locum doctors, and you can't guarantee that a locum will pick up the shifts, especially with the new cap. So already we're stretched to the very limit. I feel like I don't get to spend the time I need to with patients and extending this team any further would be catastrophic. I already feel we're on the brink of being unsafe.
"Pushing through a new contract that increases our hours and reduces our pay would see a mass exodus of junior doctors come August. We're striking now to try to prevent that."
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"This strike is not necessary, it will be damaging.
"We are doing everything we can to mitigate its effects but you can't have a strike on this scale in our NHS without there being some real difficulties for patients and potentially worse."
Cameron's official spokeswoman also told a Westminster media briefing on Monday: "We are concerned about the situation. We are doing everything we can to ensure that patient safety is protected and to provide the urgent care that patients need.
"So there have been a number of contingency planning meetings in the run-up to this strike going ahead. The Department of Health will be closely monitoring the situation and working with NHS England on that."
What Patients Need To Know Ahead Of The Junior Doctors Strike
With 30,000 operations and over 150,000 appointments each day, NHS hospitals are bracing for considerable disruption ahead of the planned walkouts by junior doctors this week.
Ongoing talks aiming to avert strike action failed last week, as the British Medical Association, which represents junior medics, announced three spells of strike action in England after its negotiations with the Government ended.
But for hundreds of thousands of patients, even the threat of strike action can provide inconvenience. Here's what you need to know about potential disruption during the planned walkout...
Your hospital will be in touch to re-arrange any operations or appointments affected by the strike - and they'll propose amended dates and times should these be immediately available.
If you haven't heard from your hospital, you can call them directly, or contact NHS 111. Make sure you have your personal NHS number to hand.