Question: what are the nioxin numbers?
Answer: Nioxin System 1 is for normal hair that'€™s fine and virgin (not chemically-treated). ... 
Nioxin System 2 is for noticeably thinning hair that'€™s fine and virgin. ... 
Nioxin System 3 is for normal hair that'€™s fine and chemically-treated. ... 
Nioxin System 4 is for noticeably thinning hair that's fine and chemically-treated.