Hi Dr Pickart,
I shampoo my hair in the morning, but apply folligen at night. Does it affect folligen's effectiveness that I am not shampooing right before application (e.g. not removing sebum build up)?

That is a good approach. The Folligen needs an few hours to penetrate into the hair follicles.

Sorry, I am a bit confused. Should I or should I not wash my hair BEFORE applying folligen to get rid of excess sebum. Or it doesn't matter?

It does not matter when you shampoo.