The King has been diagnosed with cancer, with the condition discovered during his recent hospital treatment.
The shock health news follows his treatment for an enlarged prostate, but Buckingham Palace has confirmed Charles does not have prostate cancer, but another cancer instead.
The Princess of Wales is still recovering from abdominal surgery and Sarah, Duchess of York is dealing with skin cancer.
Here is the timeline of the health troubles facing the royal family.
– Tuesday January 16
Kate, 42, is secretly admitted to the London Clinic and undergoes abdominal surgery.
– Wednesday January 17
2pm – Kensington Palace announces the princess’ operation and says she will remain in the private hospital for 10-14 days.
She is not expected to return to duties until after Easter, taking up to three months to recover.
The Prince of Wales steps back from his official duties temporarily to care of his wife and children.
The exact nature of Kate’s condition is kept private, but it is not cancerous and Kensington Palace says the planned procedure was successful.
3.25pm – Buckingham Palace announces the King, 75, is to have treatment for a benign enlarged prostate and will be admitted to hospital in a few days.
A source later says the princess is “doing well”.
– Thursday January 18
The Prince of Wales spends time at his wife’s bedside, driving himself away from the back entrance during the low-key, private visit.
The Queen says the King is “fine” and “looking forward to getting back to work” during a visit to the Aberdeen Art Gallery.
– Friday January 19
The King flies back from Scotland with the Queen and heads to his Sandringham estate in Norfolk to rest ahead of the procedure.
– Sunday January 21
It is announced that the King’s former sister-in-law, Sarah, Duchess of York, has malignant melanoma, a form skin cancer.
It is less than a year since the duchess, 64, was diagnosed with breast cancer and had a mastectomy and reconstructive surgery.
– Monday January 22
The Queen tells 86-year-old well-wisher Jessie Jackson that the King is “fine”, and thanks her for asking, while she carries out engagements in Swindon.
Sarah, Duchess of York, meanwhile, describes her shock at having skin cancer but says she is in “good spirits” and “grateful for the many messages of love and support”, in a post on Instagram.
– Tuesday January 23
Kate’s hospital stay passes the one-week mark.
Camilla urges the King to take it easy. An insider told The Sun: “The Queen has told him he needs to slow down a bit.”
– Thursday January 25
The King carried out behind the scenes official duties, meeting academics from Cambridge University at Sandringham House.
The King arrives back in London from Norfolk ready for his treatment.
– Friday January 26
The King, with the Queen at his side, is admitted to the London Clinic for treatment for an enlarged prostate and also visits the Princess of Wales, who is recovering in the same hospital.
– Monday January 29
The King is discharged from hospital and waves at well-wishers. Kate leaves the clinic the same day to continue her recovery at home.
– Wednesday January 31
Camilla says the King is “getting on, doing his best” as she opened a Maggie’s cancer support centre at the Royal Free Hospital in London.
– Sunday February 4
The King and Queen attend church in Sandringham, with Charles waving at well-wishers.
– Monday February 5
Kensington Palace confirms the Prince of Wales is returning to official duties this week, beginning with an investiture.
6pm – Buckingham Palace announces the King has a form of cancer – but not prostate cancer – and has started treatment as an outpatient.
He will not carry out public-facing duties, but will carry on with behind the scenes state business and official papers.