Hair transplant surgery is relatively low risk but like any other surgery there are open wounds that are at risk to infection. Therefore you need to be careful to follow the clinics post op hygiene routines. I work for a clinic myself and we do take this very seriously.
So basically as long as you are careful you should be clear of infection,
As for side effects, the answer is no. It may take a few months for your nerve endings to repair themselves in the donor area following FUE surgery but that's about as far as gets. In the meantime you might feel some discomfort or sensations but hardly painful.
Following surgery you are likely to be prescribed Minoxidil and Finasteride (1mg). The Finasteride can cause side effects in a small number of patients. If so it is wise to reduce the dosage, the frequency and if problems still occur then its best to stop altogether. The Minoxidil spray can cause irritation to some patients but switching to the lower alcohol content foam version usually resolves this.
Hopefully when all your hair is grown out, a side effect that might occur is the additional female attention your new locks get you, lets hope so!
For further info on good monthly growth etc you can check out my old thread in the link below.
Naa, there is no side effects or anything really. You just need to be careful about infection and protect your grafts in the beginning. But I assure you there is nothing serious about it. Only, if you use Finasteride, it is said that it kills your sex drive but it is not a common problem.
I think what you should be careful with it, planning how you want to do it. There are many successful clinics and methods but it requires some research, dedication and patience to find your ideal surgeon. I think the biggest risk is choosing a clinic where you get too many grafts and you are convinced that the result is amazing. The trick is using the least possible amount while getting a natural and dense look. Also, you have to plan ahead too because if you use too many grafts for the first surgery when your hair loss progresses, you need another surgery but don't have hair supply left because an excessive amount of hair was used in the first surgery.
I think the most important part is finding a surgeon you can trust because there is a good chance you will going back to him after years. If you want to read more, this article is very useful to build a strategy to get the most out of your hair transplant journey.
There are very low chances of risk in hair transplant surgery. All you have to do is take some precautions after surgery for the recovery period. But if you have a diabetic condition and you are having high blood sugar levels then there may be increased risks of infection after surgery.