Mohammad Abdul-Kader Al-Jassem has refused to eat or take heart medicine since Wednesday evening, the day after he was detained following a complaint against him from the ruler's office, his attorney Abdullah Al-Ahmad told Reuters.
The blogger and journalist, who is a staunch critic of the government, was accused of insulting the Emir Sheikh Sabah Al-Ahmad Al-Sabah, and inciting the overthrow of the government, according to his lawyer.
A government spokesman could not be reached for comment.
"His health deteriorated and he was taken to the military hospital yesterday," his lawyer said, adding that he did not have any more details about his client's condition.
Jassem was drinking water, but refused to eat or take his medicine until the complaint against him was withdrawn, he said, adding that Jassem believes he could face "a political trial," rather than a criminal one.
On his website, Jassem has directly criticized the ruling family and blamed Prime Minister Sheikh Nasser Al-Mohammad Al-Sabah, for mismanagement and corruption. The lawyer said Jassem was being questioned about three political books he published after they were licensed by authorities.
He said prosecutors have extended his detention for 21 days pending either a trial or further investigation.
Kuwait, the world's fourth-largest oil exporter, has a free press but many writers and bloggers have been questioned and tried for libel.
The emir is protected from criticism by the constitution.
Freedom of speech campaign group Reporters Without Borders has called for Jassem's immediate release and all charges against him to be dropped.
It said the writer was sentenced in April to six months in prison for slandering the prime minister, but the court suspended the sentence pending an appeal.
