It's impossible to go to Paris without being drawn into the pharmacies, one reason that they're there every twenty steps or so luring you in, another that they stock the best everything. My favorite brands to stock up on are Bioderma, Caudalie, Avène, Klorane, and Embryolisse. Here's what I'm using right now, along with a few I bought stateside.

1. Caudalie Beauty Elixir - This is a fine spray of essential oils that acts as a toner but I use it more to refresh my skin throughout the day and/or make my makeup look less 'done'. Feels amazing after a long plane ride. I'm also a real sucker for the word 'Elixir' and glass bottles in general.
2. Jurlique Rosewater Balancing Mist - Same purpose as the above, but a different flavor..for lack of a better word. The best rose water I've ever tried. There are a lot out there!
3. Vinoperfect Day Perfecting Fluid - This is what I use when I don't want to wear makeup, but want to have something on my skin for a little extra glow (think yoga class or the airport). I'm not quite sure what I would classify it as, maybe a slightly tinted primer or the sheerest foundation in existence. The SPF 15 is a bonus.
4. Dr. Hauschka Rose Day Cream - A super rich moisturizer ideal for travel-battered skin, this is the most popular product from the natural ingredient-focused brand. I actually use it for both night and day when I feel like I need some help from the 30 roses that go into each tube.
5. Mario Badescu Orange Tonic Mask - This mask is calming and captures the smell of oranges without going into saccharine/fake territory. I use it once every couple weeks ie. when I remember how amazing it feels.
6. Bioderma Crealine h20 - The one item I would really hate to forget to pack, this melts makeup right off your skin without any harshness or residue, acting like a slightly more powerful version of water. If water could simultaneously cleanse, tone, and moisturize. It's actually weird how perfect it is...cult status for good reason. Along with Embryolisse's Lait-crème Concentré, this is something almost all makeup artists I've worked with swear by. Stock up here.