Alexei Navalny, Russia's most prominent opposition figure, has questioned reports of an acute allergic reaction after being ill in prison.
"I have never had an allergy, not against food or pollen or anything else," he wrote in a blog post.
The 43-year-old was hospitalized on his body with swollen face, eye problems and rashes. He was in jail for invoking unauthorized protests.
His doctor suspected he had been exposed to a "toxic substance".
Mr. Navalny was released from the hospital and returned to prison.
What did Alexei Navalny say?
In a statement in Russian published on his blog and written out of his cell, Mr. Navalny said he has never had an allergic reaction in his life. He added that his wife suffers from allergies, which means he knows what they look like.
"At night I woke up with a hot and spiky face, ears and neck," he wrote. "I had the feeling that I had rubbed my face with glass wool."
"I had the thought, maybe I was poisoned."
Mr. Navalny was sent to the hospital in the morning where the doctors were diagnosed with him " contact dermatitis ".
Mr. Navalny wrote in his blog post that his lawyers and doctors did not receive a diagnosis and that a detailed detention report was made. His diagnosis to the Russian news agency Interfax was that nothing had been said to him.
Although he did not completely deny the possibility of an allergic reaction, the police at the door of his sickroom acted as if they had something to hide. ,
He said he was sure the local police had not poisoned him as "they were more shocked by the sight of me than me." He said, however, that the Russian authorities were "stupid" enough to do so.
Anastasia Vassilieva, the doctor of Navalny, told AFP before that it was "absurd to call it an allergy". He must be "under strict medical supervision" and should be allowed to call his family.
In a Facebook post, Ms Vassilieva complained that she had been denied the visit of Mr Navalny. But on the basis of what she saw through a door of his, she said that he may have been hurt by a "third-person chemical".
Before Mr. Navalny was released from the hospital, his medical team said that they were able to gain access to him and had samples of his hair and t-shirt independently tested.
Mr. Navalny was sentenced to 30 days in prison last week after calling for unauthorized protests that took place on Saturday.
During the demonstrations against the exclusion of opposition candidates from the local elections, nearly 1
"A thorn in the side of the Kremlin"
Alexei Navalny is Russia's most prominent opposition activist – and one of the most vociferous critics of President Putin.
That's why news about a sudden illness is making headlines.
Especially if it is a sudden illness that has occurred in a Moscow prison.
There is no confirmation that Mr. Navalny was poisoned. But his doctors – and his supporters – are looking forward to what triggered such sudden symptoms.
Health fears are not foreign to him. Two years ago, Mr. Navalny was the victim of a robbery. He suffered a burn of his right eye after someone threw a green antiseptic on his face.
He is a constant thorn in the Kremlin's eyes. The authorities know that the charismatic anti-corruption activist has the capacity to mobilize the anti-Kremlin sentiment as President Putin's declining personal views deteriorate.
However, it is still too early to conclude that his current state of health is related to his political views or activities.
Media reports said that about 20 people, including journalists, were arrested after they gathered in front of the prison hospital on Sunday night, where Mr. Navalny was being treated.
On Monday, however, were still about 150 people in custody. They are being tried in court and possibly charged in connection with the unauthorized rally.
Who is Alexei Navalny?
The 43-year-old made a name for himself in Russia as an anti-corruption activist.
He cited the country's biggest street protests against President Putin in 2011 and was repeatedly detained, usually for his involvement in unauthorized demonstrations.
Mr. Navalny suffered a severe acid burn in his right eye in 2017 after being attacked with antiseptic dye.  He tried to participate in the last presidential campaign, but was banned for previous convictions for fraud in a case he considered politically motivated.
What happened during the protests?
Thousands of Russians went to the streets last Saturday calling for fair elections. The demonstrations took place after 30 opposition candidates were expelled from participating in local races in September.
Officials said candidates had not collected enough valid signatures to stand, but opposition groups argued that the ban was politically motivated.
Mr. Navalny helped organize the demonstrations. Officials said they arrested nearly 1,400 people – making it one of the biggest crackdowns in recent years.
Saturday's pictures showed police in protective clothing crowding crowds from the mayor's office in central Moscow.
Several demonstrators have seen bleeding while at least two members of the security forces have suffered eye damage from pepper spray.
The Moscow mayor's office has officially approved for another protest on August 3, a report in the independent newspaper Novaya Gazeta.