Is it safe to shampoo hair twice a day 3 months after hair transplant?

On the fifth day after a hair transplant you can return to your regular hair washing schedule. 

Grafts are set by 10 days and therefore you can resume your regular hair washing regimen at that time. Unless you are very sweaty or workout a lot, twice a day shampooing is probably not necessary but it won't hurt your transplanted hair. It's important to keep your scalp clean and healthy but you don't want to dry out your scalp or hair. You can ask your surgeon or  hair dresser if they think your hair is overly dry with this frequency of washing.