Hi..
Welcome to HEALTHCARE MAGIC..
As per your query blackish discoloration of lips can occur in kids due to a few common reasons like excessive sun exposure,
Vitamin B12 deficiencies, excessive storage of Iron in body due to intake of
Iron supplements,
dehydration causing chapping and pigmentation etc..
I would suggest you not to apply any chemical based skin lightening creams or ointment, you can limit sun exposure, apply
Aloevera gel for lubrication, encourage her to drink plenty of water, give him nutritious food,fruits and vegetables.
Natural remedies like application of lemon juice on lips, application of honey can help in improvement of lip discolouration..
You should consult a Paediatrician and get advised regarding whether she needs
multivitamin or not and should be taken only after proper supervision with Paediatician..
Hope this information helps.
Thanks and regards..
Dr.Honey Nandwani Arora.