Hair Loss from Allergic Reaction to Hair Product?

My daughter use a mousse hair product that she used for several years and had an allergic reaction. Her forehead, neck, scalp and eyelids peeled. A few weeks later she notices her hair falling out. She went to the derm and he prescribed topical treatments. They said it would take a few weeks to see results and less hair falling out because of the severe seborrea? Anything you tell her from your experience.

It’s possible to have an allergic reaction to hair products, but she used that particular product for years and then suddenly developed a severe allergy? If your daughter is under the care of a dermatologist already, he/she will have more experience with allergic reactions than I would. Besides, I don’t know what topical treatment/dosage was prescribed, nor do I even know what the allergy was.