Mr Shah was taken to intensive care in Bangkok's Samitivej Hospital after he suffered a heart attack, the Nepalese embassy in Bangkok said yesterday (February 20).
“His condition is critical; doctors have not shared much information though,” Sunil Khadka, Secretary of the Non-Resident Nepalese Association in Thailand was quoted as saying by the Himalayan Times.
The newspaper reported, "Khadka, in whose apartment Shah fell unconscious yesterday night, is taking care of the former crown prince at the hospital.
"Khadka, however, was out to buy dinner when Shah blacked out. A Thai female companion of Shah had rushed him to Samitivej Hospital.
"Shah, 42, was said to be not feeling well for quite some time and was not taking food regularly for the last few days."
The newspaper said doctors today had suspected brain haemorrhage but later ruled that out after conducting an MRI and CT scan of his head.
Mr Shah was ordered to undergo a month’s drug rehabilitation treatment at Bang Jo Prison in Phuket after being found guilty of possession of marijuana. He was detained again in December for smashing property at a luxury apartment in Bangkok. He denied the charge and was released on bail.
Mr Shah became heir to the throne in 2001 after his cousin, former crown prince Dipendra, killed nine members of his family, including the king and queen, in a drink-and-drugs-fuelled rampage before apparently turning his gun on himself.
The Nepalese monarchy was subsequently abolished in 2008.