According to NHS England's chief executive, patients are "paying the price" for the health service's inability to put an end to strikes.
According to Amanda Pritchard, the next round of strikes later this month will worsen the "significant" disruption caused by this month's industrial action.
She claimed that "all sides" had failed to stop the attacks.
In July, junior physicians and consultants will participate in a combined seven-day strike.
Due to a lack of cover, Ms. Pritchard stated that the consultant strike will present a "different level of challenge.".
Ms. Pritchard said in an interview with the BBC's Sunday with Laura Kuenssberg program that the "hard truth" is that patients are suffering as a result of "all sides" failing to resolve the strike action, which has plagued the health service all year.
She said, referring to the July strike action, "There has been a significant amount of disruption, and that is only, at this point, going to get more significant as we hit the next round of strikes.".
Junior doctors voted last month to go on strike for the longest strike yet: five days in the middle of July.
After rejecting a government pay offer, they will leave between 07:00 on Thursday, July 13, and 07:00 on Tuesday, July 18.
Hospital consultants will strike over pay on July 20 and 21, a few days after that strike concludes.
Consultants' work cannot be paid "in the same way" as junior doctors, according to Ms. Pritchard.
It cannot be "business as usual in the NHS," she added, calling for the industrial action to end as soon as possible.