Is it safe to apply garlic or onion oil on transplanted hair?

It is safe to apply garlic and onion oil but not sure what the purpose of that would be. Dandruff would best be treated with Nizarol shampoo

Thank you for your question and photos.
i would advice to use it after 3 months.the number of grafts a patient will need depends on the thickness of their hair and the extent of their hair loss, which can be determined by the Norwood Scale below.
During a hair transplant, grafts are usually removed from the ‘donor area’ located on the back of the scalp and relocated to a balding area. The back of the scalp makes a good extraction area due to the high volume of hair follicles that congregate within that region that are not affected by the balding process. Specialist surgeons will remove a small amount of tissue that can grow hair and relocate it to the desired area of the head without damaging them.

You can apply it, but I'm not sure what the benefit would be. If your concern is dandruff you can consider a dandruff shampoo. If you have further concerns, contact the surgeon who performed your FUE.

Not sure why you would want to apply garlic and onion to your hair but it is safe. No side effects to doing so other than the bad smell.