What are hair transplant side effects?

Hair transplant side effects can occur and depend on type of treatment and surgeon.  Side effects from hair loss include:
Scarring- every hair transplant procedure has the risk of scarring.  Strip procedures will create a linear scar, while FUE procedures can create hypopigmentation with removal.  Scarring can be little to none with either procedure and shorter hair styles will benefit from FUE in general.
Unnatural results- Unnatural results can occur with poor angle or direction of hair placement.  A straight line and other obvious signs of a hair transplant should be minimized.  The difference between a surgeon with an artistic eye is telling here.  Patients just thinking hair is all the same are mistaken when they notice hair sticking straight off, poor coverage, weird directionality of hair.
Excessively large visible grafts- The plug look should be avoided and can be if proper placement is utilized and use of 1 hair grafts and multi hair grafts in appropriate locations
Loss of existing hair (shock effluvium)- Overly dense grafting sessions can lead to potential loss of existing hairs.  Graft angle can help here.
Infection- Rare but can occur with any procedure
Cysts- Too deep of placement of hair graft or partial removal of hair transplant grafts
Numbness- Much more common with strip procedures

Hair transplant is generally very well-tolerated, but like any procedure, does have some risks.  Some swelling, crusting (scabs), and mild discomfort are common and should be expected.  Depending on the surgeon's technique, scarring is also a potential concern, and mild bleeding and bruising are also possible.  Some patients will report some numbness or tingling at the surgical sites, and very rarely, patients may temporarily lose some of their normal surrounding hair (a phenomenon known as shock loss).
With that said, most patients do great with very few if any issues after transplant.  Hair transplant has very high patient satisfaction rates with minimal down time.
All the best,

Thanks for your question. Like any medical procedure, hair transplant does have some associated side effects, but hair loss is not one of them. Most side effects are localized and temporary and include bruising, tenderness, redness, and temporary numbness near the treated areas. If you're undergoing a NeoGraft (follicular unit extraction) procedure, some of the transplanted grafts do "shed" in the days following the procedure. This is an anticipated response and will not adversely affect your results. 

With NeoGraft, hair loss is not a side effect, but instead is a natural and needed phenomenon for the success of the hair transplantation. Once the hair follicle has been implanted to the desired area, the grafted hair will remain for a few weeks and then shed. Not all the grafted hair will shed but many will. The new hair growth will begin in approximately 4-6 months and continue to grow normally thereafter. Full results may take up to a year. As the new hair grows in, the results will look natural, healthy, and strong.

Although a lot of people worry about the "shock loss" of the existing hair after hair transplant this is an extremaly rare occurence if things are properly done. First of all we only do FUE procedures to avoid ugly linear scar in the back of the head. Also recent advances in the robotic surgery added ability to perform sites with the robot to avoid injury to existing hair. This is much more precise than human eye