Durgham al-Zaidi said Tuesday that his brother, Muntazer al-Zaidi, had suffered broken ribs and other wounds.
Thousands of Iraqis demonstrated in the streets Monday to demand the release of the al-Baghdadiya television journalist.
Protesters marched through Baghdad's Sadr City district and the Shi'ite holy city of Najaf, many waving shoes in honor of al-Zaidi's act.
Iraqi authorities detained al-Zaidi Sunday after the incident in Baghdad.
Al-Baghdadiya is calling for the reporter's release. The network said that freeing al-Zaidi would be in line with what it called the "freedom of expression" the United States has promised all Iraqis.
Iraqi officials have condemned the attack and demanded an apology from his Cairo-based employer.
The Reuters news agency reported that a Libyan charity group, Wa Attassimou, chaired by leader Muammar Qaddafi's daughter has given al-Zaidi a bravery award and is also urging his release.
The reporter's colleagues, including Iraqi journalist Zanko Ahmad, who spoke with VOA's Kurdish Service, said al-Zaidi resented Mr. Bush and blamed him for the bloodshed in Iraq.
Al-Zaidi threw one shoe, then the other, at President Bush during a Baghdad news conference with Iraqi Prime Minister Nouri al-Maliki on Sunday. Mr. Bush ducked as each shoe narrowly missed hitting his head.
After throwing the first shoe, al-Zaidi yelled that it was a "farewell kiss" for Mr. Bush, whom he called a "dog." He then quickly threw the other shoe, screaming it was "from the widows, orphans and those who were killed in Iraq."
Security officials took al-Zaidi out of the room, as other Iraqi journalists apologized. President Bush shrugged off the incident and said he never felt threatened.
Some information for this report was provided by AFP and AP. By VOA News.