Itchy Scalp now after using liquid Minoxidil

[Drekko]

Hey guys

I bought this brand of Minoxidil:
http://www.ebay.com.au/itm/MINOXIDIL...FpqhlIVwYQuTnQ

My scalp is very itch though now.. I found another forum post here and people say its the PPG that causes this? What is PPG exactly?

Also does the Regaine brand that is liquid have PPG or should I buy a foam?

And are there any other treatments or shampoos that I can use to reduce the irritation and itchyness?