I have been using catnip as a hair conditioner and hair colour for over 7 years. I also use it on my skin. I practically "live" in it, rinsed off. I still research it for current information regarding its safety. Catnip is not associated with any serious toxicities. Cautions concern its ingestion with regard to pregnancy, breastfeeding and menstrual issues. There are a few other cautions as well, all listed in the references below. I would heed those regarding topical use too. I prefer to err on the side of caution. My recipe has not changed. I still use 1 level tsp (teaspoon) to just under 300 ml of boiled water. I use the leftover infusion or tea for skin use.
I find for my hair and skin that recipe gives me the best results each and every time compared to other proportions I experimented with in the past. The one thing that frustrated me with conventional hair products was consistency. A large part of that was build-up. I no longer have to deal with that. True, things can change regarding hair and skin. However, if my hair feels a bit drier, it is usually because I used more shampoo than necessary. It is the same with my skin in general. I prefer to use fairly mild cleansing products and catnip plays nicely with both Sunsilk Lively Blonde Shampoo and Softsoap liquid soap. I can always apply more catnip but I have not found the need to change my recipe measurements.
My hair is much stronger and no longer dry and much more. I have no split ends and much reduced mechanical breakage because of catnip use and it is perfect for my skin. I now also apply catnip to my skin in the shower, after washing and gentle exfoliation with my hands (rubbing wet, water softened skin) when I do my hair treatment once a week on average and I wash my skin and face with catnip only in the mornings. I shower at night. Catnip instantly relieves any razor burn from shaving my legs and it smooths and softens my skin. I no longer require any face creams or body lotions or hand cream and have not for a long time. I do use sunscreen. I rinse all catnip off after application, leaving it on my skin in the shower until after my hair treatment is finally rinsed but rinsed off my skin right away otherwise.
I feel it is important to stay up to date on the newest research if possible on any herb or plant used for ingestion or topical use. While catnip is still not on the FDA GRAS list (generally recognized as safe), it is included in the FDA OTC (over the counter) list of remedies for ingestion as a digestive aid. While I was researching the reference list below, I included some links on catnip safety and cats. Catnip oil continues to be researched for inclusion in topical insect repellents. I have not included those links.
Before trying catnip or any herb or plant or new product topically, patch test first for allergies or sensitivities.
5. FDA OTC ingredient list (alphabetical by ingredient) 4-07-10
6. Health Canada