Crying with lash serum on should not have any adverse effects on your lashes. Lash serums are typically designed to enhance the growth and appearance of your eyelashes by nourishing and conditioning them. They usually contain ingredients that promote lash health, such as peptides, vitamins, and plant extracts.

Crying itself does not pose a direct risk to your lashes. However, excessive rubbing or wiping of your eyes while crying may cause some lash breakage or loss. It's always best to avoid rubbing or touching your eyes when you have lash serum on, as this can potentially disrupt the product's absorption or cause lashes to fall out prematurely.

If you find yourself frequently experiencing watery eyes or crying, it may be beneficial to choose a lash serum that is waterproof or specifically formulated to withstand tears. Additionally, being gentle with your lashes and avoiding excessive manipulation can help maintain their health and appearance.