Husbands Rob and Patrick, both in their thirties, were assaulted outside the Missing Bar on Bromsgrove Street in the early hours of Sunday morning.
Rob told the i newspaper that four men in an SUV shouted homophobic slurs at him and his husband after he jokingly asked them if it was their birthday as, he alleged, “they were all inhaling balloons”.
He added that the men stole Patrick’s phone out of his hand and knocked him unconscious when he tried to record the incident.
A friend, in her 20s, tried to retrieve the phone and was dragged “halfway down the street”, Rob, whose surname was not given, said. Police said the woman suffered a foot injury after being dragged along by the car.
Rob chased after the men and was later joined by Patrick, he said, both of whom were hit by the men including with glass bottles.
They were treated for their injuries in Birmingham City hospital.
West Midlands Police said the men in the car were described as being of Middle Eastern or Asian appearance.
Inspector Steve Lloyd said in a statement that the force was working “incredibly hard” to find those responsible.
“This was an absolutely appalling attack and robbery on people just trying to enjoy a night out in the city centre,” he said.
“They’ve suffered homophobic abuse before being physically injured, and we are working incredibly hard to find those responsible.
“We’ll be working closely with businesses in the area, and the Southside BID, to reassure them that we are taking this appalling hate crime very seriously.”