Why this tea formula says only one week of use maximum?

Can anyone comment why instructions say to use this this tea only one week maximum, one dose a day.
There is no detailed explanation. It is formulated for urological problems and I would like to use it for kidney cleanse.
Ingredients:
Pepermint leaf,
Root of restharrow (Ononis spinosa),
Uva ursi leaf,
Smooth rupturewort (Herniaria glabra),
Liquorice root (Glycyrrhiza glabra),
Parsley root

Is any of these herbs problematic for prolonged use?
:)

Tweet