Please more responses, I'm getting very scared

Hello MH, awhile ago I purchased the School Of Natural Healing book from you and just recently I made a formula of his for a friend who has acne. The formula is on pg. 73 and contains Burdock root, Sarsaparilla, Yellow Dock, Sassafras, Dandellion root, Prickly ash bark, Stillingia and Camomile. It says to take a tablespoonful 3-4 time daily. My question is, how long should my friend stay on this for? He has been on it for a week and feels it is helping along with better food choices. The formula made a Quart. Should he just use it until it is finished and should I make more of it then? I was thinking 6 weeks ( probaly 2 quarts worth) would be good and then to stop. I do not want to overdo it as this formula is very concentrated. Any insight would be appreciated. Thank you.