Lord Robert Winston, a professor and TV doctor who was a pioneer of IVF treatment, has resigned from the British Medical Association (BMA) over planned strikes by resident doctors.
Resident doctors, previously known as junior doctors, are planning a walkout for five consecutive days from 25 July until 30 July over a pay dispute with the government.
In an interview with The Times, the Labour peer and host of the BBC series Child of Our Time urged against strike action, arguing it could damage people's trust in the profession.
The BMA met with the health secretary earlier this week and said the government had "stated it will not negotiate on pay".
Lord Winston, 84, has been a member of the BMA since 1964.
"I've paid my membership for a long time. I feel very strongly that this isn't the time to be striking. I think that the country is really struggling in all sorts of ways, people are struggling in all sorts of ways," he told The Times.
"Strike action completely ignores the vulnerability of people in front of you," he added.
Resident doctors have been awarded a 5.4% pay rise for this financial year - which will go into pay packets from August - following a 22% increase over the previous two years.
But the BMA says wages are still around 20% lower in real terms than in 2008.
Health Secretary Wes Streeting said the move was "unnecessary and unreasonable", adding: "The NHS is hanging by a thread - why on earth are they threatening to pull it?"
The BMA's resident doctors committee co-chairs Dr Melissa Ryan and Dr Ross Nieuwoudt said they had "no choice" but to strike without "a credible offer to keep on the path to restore our pay".
Lord Winston's comments come after doctors and patient groups warned that the NHS in England was struggling to reduce wait times - a top priority for the NHS.
"Doctors need to be reminded that every time they have a patient in front of them they have someone who is frightened and in pain. It's important that doctors consider their own responsibility much more seriously," he said.