Camilla Parker Bowles' condition could be life-threatening.

The Duchess of Cornwall was supposed to join Prince Harry and Meghan Markle for an engagement on Thursday. However, Camilla was not feeling well, so she was forced to cancel her attendance. A Clarence House spokesperson later explained why the duchess missed her engagement with the Duke and Duchess of Sussex.

“The Duchess of Cornwall has been told by her doctor to cancel her engagements owing to a chest infection which has got progressively worse over the last few days,” the spokesperson said.

According to Express, the condition should be taken seriously. People suffering from chest infections are urged to get plenty of rest as some forms of this illness could be “life-threatening.”

“A chest infection is an infection of the lungs or large airways,” the NHS guidelines read. “Some chest infections are mild and clear up on their own, but others can be severe and life-threatening.”

Some symptoms include chesty cough, shortness of breath, fever, headache and tiredness. Severe chest infection can last for days and the unpleasant symptoms usually get better on their own in about seven to 10 days. However, the cough and mucus can last up to three weeks.

Due to Camilla’s condition, it remains unknown if she can join the royal family for Remembrance Sunday. If the duchess will not make it, then Markle might take her place on the balcony next to Queen Elizabeth II and Kate Middleton.

Last year, the Queen, Duchess of Cornwall and Duchess of Cambridge were photographed standing next to each other during the service. Meanwhile, Markle was positioned in different veranda with German President Frank-Walter Steinmeier’s wife Elke Budenbende.

Initially, many were wondering why Markle did not join Queen Elizabeth II, Camilla and Middleton. There were speculations that the size of the veranda was a factor. Others felt that the royals slighted Prince Harry’s wife.

According to People, their position was determined according to a “pecking order.” Camilla and Middleton being Prince Charles and Prince William’s wives, respectively, are the future queens that’s why they stood beside Queen Elizabeth II. On the other hand, Markle is unlikely to be sharing the same fate because Prince Harry is way down the line of succession.

Prince Charles and Camilla Parker Bowles Camilla Parker Bowles and Prince Charles look at each other as they reopen the newly-renovated Edwardian community hall The Strand Hall during day three of a visit to Wales on July 4, 2018 in Builth Wells, Wales. Photo: Getty Images/Chris Jackson