hair loss problem

a friend sent me a message asking me about natural cures for hair loss. You see, he has been experiencing major hair loss ever since he stepped foot on that country, most probably it's from the unruly climate or weather (or whatever you call it) that it has, causing scalp irritation thus explains loss of his hair. Actually, even my husband told me about that too after a few weeks of staying there, but he managed to get over it by giving extra care to his hair - by not using hot water during his shower and bath time (that I find very impossible to believe! lol) So there, do you have any suggestion on what to use or do for him to avoid major hair loss?