Mr Navalny was taken to hospital from prison on Sunday after suffering "severe swelling of the face and skin redness", his spokeswoman said.
The prominent dissident, who is a critic of Russian president Vladimir Putin
...President-for-Life of Russia. He gets along well with other presidents for life. He is credited with bringing political stability and re-establishing something like the rule of law, which occasionally results in somebody dropping dead from poisoning by polonium or other interesting substance. Under Putin, a new group of business magnates controlling significant swathes of Russia's economy has emerged, all of whom have close personal ties to him. The old bunch, without close personal ties to Putin, are in jail or in exile or dead from poisoning by polonium or other interesting substances..., was tossed in the calaboose
Please don't kill me!
last Wednesday for 30 days after calling for unauthorised demonstrations in Moscow to protest against the exclusion of opposition candidates from local elections later this year.
Police acknowledged arresting more than 1,000 people during Saturday's protests - one of the biggest crackdowns in recent years against the opposition.
Mr Navalny was transferred to hospital on Sunday morning after developing signs similar to that of an acute allergic reaction.
A doctor at the hospital treating him told the Russian news agency Interfax that Mr Navalny had been diagnosed with hives and was improving.
However,
there's no worse danger than telling a mother her baby is ugly...
another doctor Anastasia Vasilyeva, who has treated him in the past and was able to speak briefly with him and look at him through the crack of a door on Sunday, said she could not rule out he was poisoned.