The agency won the account following a competitive pitch.
PitRok is a range of natural, skin-friendly deodorants, hair and skincare products that are gentle enough to be used by expectant mums and those with sensitive skin.
They contain natural, organic ingredients, are fragrance free and are suitable for vegans and vegetarians.
The agency will also promote Severn's Sarah Smith range, which is a collection of cleaning and home products that are Fairtrade.
The London-based PR shop has been briefed to start on a retained basis.