Yes. On the internal studies we noted mild scalp irritation in less than 2% of the subjects which was temporary and self limiting. The irritation was mainly due to Niacin which is an irritant and causes vasodilatation which helps in absorption.

[Note from HairlossTalk.com - those that do experience irritation find it helpful to apply Revivogen an hour or two before bed, and then wash it off in the morning with their normal daily shower. This tends to limit any irritation that may otherwise be experienced by keeping it on all day long].