Mixing eye drops into your eyeliner is a well-known trick to help bring it back to normal consistency, and all you need is a dry gel or cream liner, a toothpick, and eye drops.
Add the eyedrops to the eyeliner and then mix them together thoroughly. Depending on the consistency, this could take a few minutes, but you want it to be as smooth as possible.
You’ll need to place your eyeliner in an airtight container or plastic bag and leave it in warm or hot water for up to 15 minutes, but times will vary.
If you want to give your eyeliner a second chance, try applying pressure with the back of your hand. It will only work for pencil and felt-tip liners and may kickstart the product.
Sometimes, the simplest method is the most effective, and a good shake can go a long way. Doing this before every use is recommended, not only when the product is getting dry.