Can I use use eyeshadow applicator brushes instead to apply my Latisse?

Yes, if you can't use the original Latisse brushes then you can use a thin eye liner brush to apply Latisse. It will give more precision than a normal shadow brush.

I don't think that's a good idea. You want to be able to precisely control the amount of latisse applied and where. It's best to use the applicator brush that comes in the package or a very fine eyeliner brush but then make sure to clean it thoroughly after each use. Best, Dr. Nazarian

I suggest using the applicators that come with
Latisse. The recommended usage is one applicator per eye, but some of my
patients tell me that they use one for both eyes and then dispose of that
applicator. The issue with eyeshadow applicators is that they often have a
sponge tip that will absorb the product. That means less will go to the lash
bed and that may affect the results. Also, unless you are using a new eyeshadow
applicator with each use, it won’t be as sanitary.

Thank you for your question. It is not recommended to use a different brush than the one provided, the applicators in the box were designed for the product and ensure you are despensing the appropriate amount for best results. An eyeshadow applicator may absorb to much of the product. Best wishes,Pablo Prichard MD

The Latisse applicator was specifically designed for applying Latisse. That said, if you're able to carefully apply in a similar manner with a different brush which doesn't absorb too much product (wasteful/costly), then there should be no issue.

Sure, you can, but be warned that the Latisse brushes are made so that they don't absorb excess product and allow you to get the most bang for your buck.. Many makeup applicator brushes can absorb product so that means you won't be getting as much on your skin. "This
answer has been solicited without seeing this patient and cannot be
held as true medical advice, but only opinion. Seek in-person treatment
with a trained medical professional for appropriate care."