Russia's most prominent opposition figure, Alexei Navalny, was taken from jail to a Moscow hospital.
Officials gave no details of his condition, but Navalny spokeswoman said he had an allergic reaction with severe facial swelling ̵
A hospital source told the Russian media that his condition was satisfactory.
Mr. Navalny was sentenced to 30 days in prison last week after calling for unauthorized protests that took place on Saturday.
More than 1,000 people were arrested during demonstrations against the blocking of opposition candidates in the upcoming local elections.
The European Union criticized the "disproportionate" use of force against demonstrators and undermined the "fundamental freedoms of expression, association and assembly".
How is Nawalny treated?
Nawalny spokeswoman Kira Yarmysh tweeted that the opposition leader has never had an allergic reaction.