Generally my advice to patients is to avoid getting a sun burn on the scalp after a hair transplant surgery. Wearing a hat is a great way to prevent prolonged sun exposure and run the risk of a sun burn on the transplanted zone. Scratching and itching usually resolves on it's own and additional washing can help.
It is always a good idea to avoid direct sun exposure especially after surgery. It is also a good idea NOT to keep scratching the transplanted area. Use common sense and judgement.
Usually the patients recipient and donor area should have been healed by now. In some cases itching of the donor area is normal and may take up to six to eight weeks for the itching to go away. If it continues he needs to be seen by his doctor. You need to encourage him to stop itching the area. If he is in direct long exposure to sun he needs to wear a hat, otherwise it is not necessary.
Scratching is dangerous as it induces infections in the follicles that were transplanted. The finger nails are not sterile, they are dirty from a bacterial point of view, so scratching the itchy scalp runs the risk of producing damage to the recipient area and introducing an infection which could lead to folliculitis. Infections then need to be treated quickly so if there is redness in the area he is scratching, he should see his doctor.
A month after a hair transplant is when the grafts are already sealed in their new nests. Some itching and occasionally inflammatory pumps may occur at this time, but they should become better as time passes.
I generally advise my patients to use a cap or sunblock to avoid sunburn since it may damage the transplanted grafts as well as native hair of the scalp. After the first six month and when the hair coverage is present, it can minimize the risk of sun burn.
It is always important to protect your head against the sun in the first 3 months after the surgery. If he works outside it is best to cover up with a cap. The itching is not necessarily bad because that can happen in the first months after surgery when the skin is itchy still