Excessive gum chewing, particularly on one side of mouth, can strain temporomandibular joint, leading to jaw pain, headaches, earaches and difficulty chewing, said Dr Ninad Muley. Even sugar-free gum can contain acidic flavourings that, when chewed for long periods, may contribute to dental erosion. Constant gum chewing can cause excessive air swallowing, leading to bloating, gas and discomfort.