This is just my experience with the ketamine cream. Your reactions could be different.
I use a cream that is 10% ketamine hydrochloride with some other ingredients... I typically use it on the entire top of one foot, about 1/3 of one calf, on one upper arm, and about 75% of my back. I am allowed to use it 4 times a day.
I don't use it right after getting out of the shower, or when my skin temp is really warm, as it seems to work a lot more then... I have had my tongue feel numb before from doing this
but have had no other problems.
Oh... and one time, my massage therapist was putting it on for me after a session. It was the first time she applied it. She was expecting a thicker cream. It is almost a watery liquid. When she went to pour a small amount onto my back, a lot came out, and so she just rubbed it in. Again, I think my skin was warm from the massage.... I did get a light-headed feeling for about half an hour. This was using about 3 times the normal amount. I did not feel really impared... just like I had perhaps a half glass of wine. My massage therapist does apply it with gloves though - she is afraid it might numb her hands - not good for the next patient
I like the lidoderm patches because they last longer... a lot of my "areas" are in places I cannot reach, so cannot apply more cream once I am at work. So, I use the patches on those areas, and then use the cream on the places I can easily reach to re-apply. On days I don't work, I use the cream only.
If your read the links to the other posts... you will know that I really believe that the base used for the cream makes ALL the difference.