Thai citizens started wearing pink en masse yesterday as soon as word spread that the colour has "auspicious power" for their beloved King's good health.
HM King Bhumibol Adulyadej, now 88, has been receiving treatment at Siriraj Hospital for several years.
"I am wearing pink for my beloved King," Urisara Kowitdamrong said from her office in Bangkok. "All my family members are also in pink today."
Pink looks set to become a big trend again, repeating the phenomenon that grabbed Thais in 2007 when the colour was said to be good for the much-revered monarch's health.
Jirawan Viriyasiri, a former bank employee, said: "I wear pink to express my loyalty and deep concerns for HM the King's health… I plan to wear this colour as often as I can. If possible, I want to wear it every day to show my best wishes to the King."
Sitting on the throne since 1946, the King has commanded much love and respect from his people. He is also the world's longest reigning monarch.
On Sunday, the Royal Household Bureau released a statement on the King that said his condition was not stable.
This spurred a huge number of Thais, concerned about his well being, to begin praying for His Majesty to have better health.
Many posted messages on social media wishing him a quick recovery. They also started wearing pink to show their love for the monarch.
Nusara Nacharoen said she had never hesitated to show her respect for the King. "I plan to wear pink this whole week," she said.
A look back at Thailand's King Bhumibol Adulyadej's life
Nusara said she was always keen to do whatever she could to show her loyalty and moral support for the King. "I also joined a religious praying rite held for his recovery," she said.
A map of Thailand painted pink with the message "Thailand will be pink tomorrow" was also shared on social media many times yesterday.
Many people wearing pink headed to the Siriraj Hospital yesterday to write get-well messages and pray for His Majesty to recover.
Prime Minister General Prayut Chan-o-cha along with his wife, plus military leaders, members of the National Council for Peace and Order, and Cabinet ministers, left well-wishes for the monarch at Sala Sahathai Samakhom in the Grand Palace, while wearing pink and yellow.
The pink trend has spread across all provinces too.
In Yala in the far South, a resident said she put on pink clothes after finding a message on a chat application that pink would be good for the King's health. "I wish him a quick recovery," she said.
In Ranong province, Kanrawee Charoenvipasjet, 36, said wearing pink was her way of showing best wishes and loyalty to His Majesty. "We are praying for him too," she said.