Thick white layer(dandruff?? Deadskin??) On scalp 4 weeks post FUE hair transplant.

It is best to contact your doctor about post operative care and instructions since each doctor has a different regimen.  You may have issues with dry skin.

Briskly wash your hair & scalp daily with 2% ketoconazole shampoo. Schedule a follow-up with your doctor after 7 days if no improvement.

After Hair Transplantation, every patient has scabs ( similar to dandruff) and normally I expect my patients to loose them and have clean scalp in 2 weeks post operative. For that I require my patients to follow every step of post operative instruction, and use the products for moisturizing the surgical area and not having any dandruff, otherwise it may give a harm for transplanted area. You should consult with your own hair Surgeon in order to get prescribed suitable products for your scalp.

It is difficult to determine what you are meaning without photos. Please resend it again with photos so we can see what you are talking about.  An FUE is treated just like a regular hair transplant with regard to the recipient area, but the donor area has open wounds which require daily washing with soap and water. Within 3 days of surgery, you can resume full activities, heavy exercises if you wish. The recipient area requires daily washes as well to keep the recipient area free of crusts. I generally recommend the use of a sponge and supply my patient with a surgical sponge to fill with soapy water and press on the recipient area daily. By repeating this daily, all crusts can be washed off without any fear of losing grafts. IF any crust is present, use a Q tip and dip it into soapy water, and roll it on the crusts and that will lift them off without dislodging them, but never rub them, just roll the Q tip on the recipient crust. I like to see no evidence of any crusting in the recipient area and the crusts from the donor area gone in 3-4 days with daily washing.