Am I having a bad reaction from Restylane I got 2 days ago? I'm having flu-like symptoms, and nightmares. Done by a NP for 300$

These symptoms are unrelated to your filler. If they persist, I recommend following up with your Doctor for an evaluation. Best, Dr. Emer

I would see your primary care doctor as this is not associated with having a dermal filler. On the plus side $300 is a great deal! Hope you feel better. Dr. M

It is highly unlikely this is from the Restylane..You could possibly have the Flu. However I will say with over 30 years of injecting fillers I have had a couple of patients say they did not feel good after injections. Most likely flu but f you truly think it's from the filler I would avoid them in the future.. Time will tell while you recover...this is flu season. Please call the office of your injector and discuss this with them.I am concerned about your Restylane. If you had a 1 cc syringe injected the product costs us more than $300, If it was 1/2 cc then this is possible.I would wonder about the product if the price is too good to be true.I hope you are feeling better soon.

These symptoms are not due to the injection of the product. contact your family doctor to see what is going on

I say generally not related because flu like symptoms and nightmares are not documented side affects of dermal fillers.  When you say flu like symptoms are you talking about body aches , high fever, cough ?  It could be that you do have the flu but the other worry would be if there is an infection from the injection. If that was the case the area would likely be red hot and tender as well.
I would discuss this with the NP. 
Nightmares are unexplained.
Finally cost that price may be under cost, and that always concerns me when a patient says the got a bargain injectable and they pay less than what it costs me to purchase the product. 

I am sorry to hear you are not feeling well, however I can assure you that this is unrelated to the filler. I would advise seeing your general practitioner. If you are really concerned that it's related to the filler, I would advise calling the office where you had it done and explaining your symptoms, however as I mentioned before, Restylane or any of the fillers for that matter, do not cause these kind of symptoms.