At 16 they will probably refuse to you the good old finasteride/minoxidil
But first, you need to see a dermatologist asap, because it can be stress related or non AGA, like a telogen effluvium phase, or comes from a skin condition like psoriasis
Second, the non-invasive treatments are ;
1/ Multivitamin/Zinc supplementations, alongside eating a lot of sardines for the collagen, iodin and Omega 3 and Vit D boost.
Biotin doesn't work btw
2/ A topical solution with a base of 30% alcohol, with 35% Castor Oil and 35% Rice Bran Oil, and then you add 5% Rosemary oil, 5% Tea Tree oil, 1% Caffeine and 1% Melatonin with few drops of vitamin E. Caffeine and Melatonin powders need to be mixed in the alcohol before adding oils.
3/ Nizoral Shampoo 1% or getting the prescribed 2%, alongside mild anti hair loss products like Piroctone Olamine, Selenium Sulfide and Zinc Pyrithione based shampoos
4/ A micro needling device
5/ Tretinoin, but it's prescribed