Applying Vaseline or Shea butter each night is also effective to
lighten dark lips. Maintain a healthy lifestyle by exercising regularly and consuming a balanced diet consisting of fruits and vegetables. Fresh fruits like oranges, guavas, strawberries, papaya, etc. contain a good amount of Vitamin C to lighten the skin. Drink 2-3 litres of water every day .This is merely an advice. For more queries and assistance visit a dermatologist. I hope it helps.
Best luck and regards!