If I keep my contacts in while using Latisse, does it make it less effective or not work at all?

The key is to wait about 15 minutes after applying Latisse before re-inserting as this gives the product enough time to dry. The product can adversely affect your lenses, which is why they should be removed before application. 

Wearing your contact lenses will not alter the effectiveness of Latisse. Administer the product as directed. In some literature you may read to remove contact lenses in case the product is accidently placed in the eye. In which case you would have to flush the eye out with water / normal saline to remove product. When flushing the eye it would be best without the contact.Apply as directed and you will be fine.   

Thank you for your
question.No, as long as you are applying Latisse correctly, it should not interfere with wearing your contact lenses.

To be sure, see
two or more board-certified providers in your area for a complete evaluation to
make sure you are a good candidate and that it is safe for you to have Latisse.

I hope this helps.

That I will trials are performed with Latisse were executed in the absence of contact lenses.  The labeling for this product therefore indicates that contact lenses should not be worn when the pieces applied.  From a practical standpoint, it is best to avoid getting Latisse into the eye for multiple reasons.  If you wear contact lenses, in my opinion it is okay to use Latisse with your lenses in but I would take care to avoid getting a product and your eyes.

Wearing contacts while applying latisse correctly is fine.  As long as you are applying it as directed (along the upper lid lash line at bed time), you will get the desired result.