Hi... Hyperpigmented lips is because of excess production of skin pigment melanin... Reasons are sun uv exposure, hormone imbalance, tobacco chewing, smoking, in females during pregnancy in some cases, hereditary, over stress, insomnia, digestive troubles also affected mucous membrane issues, exposure to some of medicine reactions (use of antimalarial drugs &antibiotics like oral minocycline), Addison disease like some health issues, lip balms or lipsticks also one of the reasons... In homeopathy we can give better results in this cases...