Paranix products do not contain any chemicals. Instead, they have a purely mechanical mode of action, which means head lice cannot develop resistance to any of its ingredients. An apparently treatment failure is more likely to be the result of:
- a bad diagnosis.
- failure to follow instructions: not enough product, treatment duration is too short, lack of head lice and eggs removal by combing, etc.
- (re)-infestation by untreated school friends, family members including adults.
- no cleaning and disinfection of the surroundings.
- not checking 7 days after the first treatment or repeating the treatment if necessary.
Unlike for Paranix, resistance of head-lice is a known issue with insecticide-based treatment products.