Bolsonaro, 66, was diagnosed with an intestinal obstruction on Wednesday evening after being taken to a hospital in São Paulo, according to state-run news agency Agência Brasil.
While it was initially feared that Bolsonaro would have to undergo emergency surgery, doctors said he would be receiving “conservative clinical treatment” for now.
The president shared a photo of himself in hospital on Twitter, writing: “We'll be back soon, God willing. Brazil is ours!”
The Brazilian leader had initially been taken to the Armed Forces Hospital in Brasilia, but was transferred to the Vila Nova Star Hospital in São Paulo for further assessment, physicians said in a statement published by Agência Brasil.
“After clinical, laboratory and imaging evaluations carried out, the president will initially remain hospitalized under conservative clinical treatment,” said the statement, signed by chief surgeon Antônio Luiz Macedo and others.
In recent weeks, Bolsonaro has appeared to struggle with speaking on various occasions and said that he suffers from recurring hiccups.
“I apologize to everyone who is listening to me, because I’ve been hiccupping for five days now,” the president said in an interview with Radio Guaiba on July 7. He suggested that some medications prescribed after dental surgery might be the cause. "I have the hiccups 24 hours a day.”
The following day, during his weekly Facebook Live session, Bolsonaro apologized again for not being able to express himself well due to the weeklong hiccups.
There are concerns that the obstruction could be related to a 2018 incident that saw the far-right leader stabbed in the intestines while campaigning.
The president has had to undergo several operations since the stabbing, which saw him lose a significant amount of blood.
Bolsonaro’s son Flavio has previously described his father as “almost dead” by the time he made it to a hospital following the attack.
In a tweet on Wednesday, Flavio thanked well-wishers for their “recovery messages and prayers” after his father’s hospitalization.
“May God give everyone everything they want from my father in double...right now!” he said.
Bolsonaro’s hospitalization comes as his popularity has taken a significant hit, with the Brazilian leader facing allegations of corruption and widespread criticism over his handling of the Covid-19 pandemic.
Recent polls have shown record-low approval ratings for the far-right leader.
A poll released earlier this month by Datafolha found that 54 percent of Brazilians would support impeachment proceedings against Bolsonaro, painting a bleak picture for his re-election bid next year.