The man was spotted by a passerby on Wearmouth Bridge, who became concerned for his safety due to his heavily intoxicated state.
Officers attended the scene along with the ambulance service and the man was taken to hospital where he received treatment before being released.
Neighbourhood Inspector Tony Carty said: “People need to be aware of the dangers of these substances. These are sold as a herbal incense only and should never be consumed.
“As proven in this case, the person didn’t only require hospital treatment because of the effects of the drug on his health, but he also put himself in a vulnerable position where he could have caused himself injury or worse.
“Thankfully a passerby contacted emergency services before anything serious could happen or any more of the incense could be consumed.
“Using legal highs, in the way they are intended or otherwise, isn’t safe and we would urge people to steer clear of them. They can kill or have a devastating impact on someone’s health as they often contain potentially dangerous chemicals.
“Anyone who misuses drugs, prescribed or non-prescribed, is putting their life at risk and people should also be aware that this risk is significantly increased if mixed with alcohol.”
This is the latest in a number of incidents involving legal highs in the North East.