Water-based lubricants can be used with menstrual cups. We highly recommend the Merula Menstrual Cup Lube which is designed for use with menstrual cups.
Please do not use oil-based or silicone-based lubricants as the ingredients may degrade silicone, rendering your cup unusable. We also recommend avoiding lubricants that contain glycerin. Glycerin is a sugar alcohol compound, and can feed yeast in the vaginal environment, which may cause yeast infections or thrush.