Queen Elizabeth II and Kate Middleton are reportedly both suffering from an "incurable sickness," a royal expert claims.

A report from Express noted the two royal ladies have motion sickness and it is something they couldn't escape during royal events. This claim comes after the Duchess of Cambridge was seen "moody" while they were at the horse-drawn carriage ride during the Trooping the Colour. But, Sunday Mirror reported Middleton has just struggled with the swaying of the vintage coach.

Queen Elizabeth reportedly recommended her granddaughter-in-law a medication, but the effective one can make those who take it drowsy. According to a royal source, Middleton gets "very seasick," and she does not enjoy the carriages' rocking motion.

The insider said the Duchess of Cambridge is worried she might be ill on such an important occasion, like the Trooping the Colour, and it reportedly added to her stress. Furthermore, the royal protocol meant she had no choice but to go by the state carriage.

Queen Elizabeth, on the other hand, reportedly admitted last year that her coronation in 1953 was very uncomfortable. She described the two-hour journey in a 200-year-old, 24ft, four-ton carriage pulled by eight horses as "horrible." She added the sickness sprung on leather and not very comfortable.

Meanwhile, as per Dr. Qadeer Arshad from Imperial College, motion sickness is said to be down to mixed messaged coming from the ears and eyes. He said the most effective drug could make people drowsy, so it isn't recommended for royals to take it before attending royal engagements.

But, he also said there might be a suitable treatment for motion sickness in the future. He noted they had developed a technique where it uses electricity so it can stimulate parts of the brain to ease the symptoms. Meanwhile, the Buckingham Palace was reportedly unable to comment regarding Middleton's seasickness.

In another report, Queen Elizabeth, Middleton, and Prince William were spotted last week during the opening day of the Royal Ascot. The three were joined by other royals, such as Camilla Parker Bowles, Prince Charles, King Willem-Alexander, and Queen Maxima.

Her Majesty wore an elegant blue dress coat and was photographed waiting alone. Footage also shows the monarch turned around to Prince William and Middleton, who are both seemed distracted before they walked in a different direction. The royal couple was also seen sharing an umbrella, which many felt it was reminiscent of Meghan Markle and Prince Harry's special moment during their Dubbo visit.