Are Henna Tattoos Dangerous

Where do the henna tattoo shops in beach stores and such get there designs?

My family goes to the beach every year and for the past 3 I've gotten tattoos. I'm wanting to see where I can order some of their ink and designs so I don't have to wait a year to get a temp tattoo. Especially cause I would never get a real one. I know Henna ink is potentially dangerous which is why I'm getting Jagua ink instead but I don't know where to find designs and stencils.

Henna is only dangerous if you use black fake chemical dyes.
Jagua has a high incidence of rash and sensitivity for many so do a test patch first.
I get great stencils and supplies for henna here.http://www.hennacaravan.com/shop/glitter_tattoo.html
and fresh safe henna as well.