1. Additives such as sugar and pigment in cola will affect the chemical reaction of hair dye solution, make the dyeing effect unstable or cause problems such as discoloration and decoloration.

2. Coke contains high concentration of carbonic acid, which will cause irritation and damage to scalp and hair, leading to discomfort and even allergies.

3. The gases and compounds produced by the mixing of hair dye and cola will have adverse effects on the environment and health, such as odor and pollution.