The Metropolitan Police described the incident as "football-related".
A spokesman said a man had been arrested in the area for a public order offence, unconnected to the damage at Piebury Corner.
A man in his 40s was taken to Whittington Hospital in north London with cuts to his head.
A London Ambulance Service spokesman said the man's injuries were not thought to be serious.
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Shadow business secretary Rebecca Long-Bailey has called for "immediate" relief to prevent thousands of companies going out of business.
A spokesperson criticised the behaviour of a "small number" of fans at the game between Birmingham City and the Wolverhampton Wanderers.
Those taking part in the bizarre trend say the combination of fruit juices and hot water makes for a uniquely liberating experience.