Underarm makeup

Maybe try airbrush foundation under your arms? It’s supposed to be waterproof and non-transferable.

I think foundation would stain your dress (airbrushed make up may not, but pretty sure this is going to be awkward as whoever is getting ready with you will watch this being applied). Unless you plan to be throwing your arms over your head a lot (exposing your arm pits), I wouldn’t be concerned about it. If it still really bothers you, maybe visit a dermatologist? Perhaps they could recommend or prescribe something to help?

I would stay away from anything having to do with make-up and underarms. You could visit a dermatologist but I know there are several beauty YouTubers who tackle this issue. Maybe look on there and see if there is a remedy that they have found! The internet is really a treasure trove for these kinds of things.

Try a mixture of baking soda and lemon essential oil. Make a paste with it.

Rodan + Fields has stuff for that

Visit a dermatologist! I had a similar thing going on - and a simple shampoo prescribed by the doctor got rid of it in three days after dealing with it for years!

I definitely agree - go see a dermatologist! For me, I ended up getting laser hair removal on my underarms, and within two or three treatments, that darkness is gone. It is so worth it. But as your wedding is soon, dermatologists will definitely be able to help most in the short-term.

Lots of people have dark underarms. It’s nothing to be embarrassed about!

If this is an area of concern for you, could you instead ask your photographer to edit any photos where your underarms show? Even in a strapless dress, I think the only times your underarms would show is during dancing/a bouquet toss. Better to avoid shop it out of photos than risk ruining your dress. Also I feel during dancing, the lights are usually dim, so no one will notice it. There will be so many wonderful things for people to focus on about how wonderful you will look that I'm sure their minds won't go to your underarms at all!