Is it permissible to use a dye-free cream to restore hair's blackness as a treatment for graying?

Scholars have differed regarding dyeing hair black, with some deeming it disliked and others forbidden. The preponderant opinion is that it is forbidden. The cream that restores hair to its black color falls under the general prohibition against black dye, as its purpose is to change gray hair to black. It has been reported from the Prophet, peace and blessings be upon him: "Change this with something, but avoid black." It has also been reported: "There will be people at the end of time who dye their hair black like the crops of pigeons; they will not smell the fragrance of Paradise." What may be permissible is that which strengthens the hair and maintains its original blackness without changing gray hair. However, if the cream changes the hair's true nature to become permanently black, it is likely considered a permissible treatment, as long as it does not cause harm or contain religiously forbidden ingredients. Nevertheless, avoidance is preferable, and it is better to dye gray hair with henna and katam.