Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain redness on the face in the areas where you applied Melas cream to reduce pigmentation has caused an allergic reaction [Contact Dermatitis] to any of the components of the cream leading to redness and burning sensation.. You should completely avoid using Melas cream and whenever you use any cream in future always do a Patch test by applying the cream on a small portion of skin of the inner aspect of forearm and observe the effects for 48 hours.. If there is nothing wrong then you can proceed with applying on face.. As of now you can take anti histamines like Levocetrizine for relief.. You can do cool compresses on face and also splash cool water multiple times a day... Hopefully the redness will resolve.. But in case if it still does not resolve and there is persistence of symptoms consult a Dematologist and get evaluated and he can advise you a low potency steroid ointment for relief.. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.