When can a comb be used for newly transplanted hair?

You can comb your hair after surgery.  Just be careful and follow your doctor's instructions.  You won't be able to comb your transplanted hairs until it has grown out.

Following hair transplant the donor area is safe for combing after just a few days.  The recipient site should be avoided for a longer period of time.  By 2 weeks is likely a safe time to comb, but some would advise sooner.  It is best to get a recommendation from your surgeon and follow their advise. 

A newly transplanted hair can actually be combed after a few months. The transplanted hair that are placed  are very short and really not long enough to be combed until it start to grow.  

Your recipient site from hair transplant should be quite safe at the two week point in general, but this is a question to ask your surgeon for a more specific answer. Good Luck!

Be sure to check with the surgeon who performed your procedure as there are variations in recommendationsNormally, combing hair is fine at day 10. Remember, the new transplanted hairs are very very tiny - too small to be combed ! So it's actually the existing hairs that get combed. Also, the new hairs fall out at 3-4 weeks post op so the only thing left to comb is the original hairs (until the new hairs come back up at 3 months)

In FUE, you can use a comb as soon as 7 days in most cases.  FUT should be about the same.  However, it is important to discuss all the details directly with your physician to make sure you dont have any exceptions to be concerned about. 

I am not sure if you have hair around the recipient grafts. If this is the case, you can use a comb after a week easily but be gentle. 

You can return to your normal routine after you are completely healed, which is usually around the two weeks mark.

Your question can be interpreted a number of ways. The hair surrounding the donor and recipient sites can be carefully combed a day or two after surgery. If you are asking when the transplanted hair will be  long enough  to effectively be combed, you are looking at 5-9 months after a transplant.