The reason why these oils are risky is that they contain compounds such as terpenes, ketones, and phenols. Your cat’s liver cannot metabolize these chemicals, as it doesn’t have the enzymes necessary for processing and excreting them. As a result, there is always a possibility of their accumulation in the liver building to toxic levels.
I didn't say it was safe! Just safer than minoxidil :)
The oil is usually meant to be used as a pre-wash treatment, so it's not going to sit on your head all day like minoxidil, further reducing the risk of contact with pets.
Looking on Amazon the price per liter ranges seem very similar to Minoxidil, maybe a little cheaper. First glance the cheapest Minoxidil product I could see was around 111€ / L, the cheapest rosemary oil bottles seem to be about 80€ / L - probably because most are sold as "essential oils".
That being said, it seems you're supposed to further dilute the oil so I guess it would last quite a bit longer. Still, from what I heard you need to continue to use that stuff or you'll lose the gained hair again.
The rosemary oil should be diluted in a carrier like argon oil (but it could be something else like jojoba, squalane). At around 3% concentration. So yes, much much longer!
Yes much like Modoxinil, you need to keep using it.
That's kinda another 80€ / L though. Not sure how you'd get to 3% when the article states like 5 drops per ounce of shampoo as an example, which would probably be around 1 drop for a regular amount of what you'd use to wash your hair with.
It's not, and it is actually cheap-ish. The Ukraine war obviously pushed the prices quite a bit but it is still far cheaper than something like argan oil.