Forgot to rinse with water after TCA peel. Will this have a terrible effect?

TCA peels once they have denatured the keratin and other proteins and you get "frosting" self neutralizes and reaction stops.  Think of it like this, once the protein in egg whites has been heated and turned white, you can't continue to turn it more white. The chemical reaction has occurred.  Optimal post chemical peel treatment is under the guidance of a cosmetic dermatologist.  Good luck. 

Chemical peels are the mainstay of our Rapid Exfoliation Protocol.
Used with skin brightening creams, they can improve skin quality. If the
chemical peel is used alone, PIH may develop; prompting us to begin
depigmentation protocols. 
Best, 
Dr. Karamanoukian
Realself100 Surgeon

Yes, once frosting occurs, the TCA chemical self-neutralizes and is no longer active.However, I don't recommend doing peels yourself, due to the risk of complications.Sun protection is essential. I recommend getting a formal evaluation with a cosmetic dermatologist for after care and treatment. Best, Dr. Emer

TCA peels self-neutralize in the dermal layer. This means you do not have to wash it off. That being said, TCA peels are highly variable in their effect depending on the concentration, age of the solution, and method of application. Even a light TCA peel concentration can cause severe burns if done improperly. It is best to have a medical professional apply your TCA peel under a controlled setting for the safest and best results. Hope this helps!

Johnson C. Lee, MD
Board-Certified Plastic Surgeon

Once it frosts (pin point in this case- if its two coat 15%), then the peel is over. Rinsing off with water will not make a difference. What will make a difference is post peel care- the usual emollients, SPF and barrier protection. All the best, Dr Davin Lim. Brisbane.