The primary reason men lose hair is hereditary. It can come from the father’s side or the mother’s side. What we inherit is a sensitivity to the male hormones. The hormone which is the most toxic to the hair is dihydro-testosterone. The action is similar to an allergy but not a true allergic reaction. A true allergic reaction is an antibody-antigen reaction. This is more like a toxic reaction.

Some men receive genes for minor hair loss and others receive genes for major hair loss. Male pattern hair loss, which accounts for the vast majority of hair loss in men, but not all of it, continues throughout a lifetime. Thus, as men get older, the balding or thinning area gets larger. The hair on the sides and back, the so-called donor hair, always gets smaller and occasionally gets thinner especially with very advanced age.

There are a few other special cases such as scarring alopecia or alopecia areata which do not follow this pattern. These these cases are rare.
Paul M. Straub, MD, FACS

Thanks.
-JB

You should not get excessive sun on it until the hair grows. You don’t have to bother for short intervals such as walking across the parking lot to your car but if you are going to sit out at a ball game or work in the yard or polish the car it must be protected. A serious sun burn may stop the new hair from growing. A suntan on the scalp may not look good. You won’t be able to see the grafts but if you get a suntan there are tiny pieces of skin around the grafts which have never been exposed to sunlight, they sit in the skin on the to of your head which has probably had more sunlight than any other part of your body. When you get a suntan you will be able to see the grafts. the grafted area will take a mottled appearance. Later as time goes on the new skin will become used to the sunlight and this will not happen.

You can protect the grafted area in several ways. Of course you can wear a cap. Many people have hair that they can comb over the grafts to protect from the sun. Or you can use sunscreen. You should be putting sunscreen on your face; just continue it over your head if you don’t want to wear a cap. For example, if you go to the beach and want to go in the water, put a heavy coating of waterproof sunscreen on your face and head.