Topical metronidazole is a widely used first line treatment for erythemotelangiectatic and inflammatory rosacea. Commonly, a moisturizer is also used to restore the skin barrier and reduce inflammation. The purpose of this study is to assess the whether the common practice of applying moisturizer prior to topical metronidazole affects this medication's stratum corneum penetrance in rosacea patients. Participants will have one research office visit that will consist of having a randomly assigned combination of metronidazole and one of four moisturizers applied to their face, followed by non-invasive tape stripping of skin at the 1 hour and 4 hour time points. These tape strip samples will be analyzed with liquid chromatography mass spectrometry (LC-MS) for assessment of metronidazole penetrance in the stratum corneum in the presence of moisturizers. The target population will be rosacea patients in the age range of 18-60 years of age. This study has minimal risks/safety issues as topical metronidazole is an already FDA approved medication with an indication for rosacea and all investigated moisturizers are over-the-counter formulations commonly used within the rosacea patient population. Tape stripping will remove 5 levels of superficial stratum corneum, and will not result in bleeding, scarring, or other prolonged cosmetic disfigurement. Small, transient bruising may result from tape strip collection. The collected samples will have no to minimal biohazard risk, as the collected specimen for analysis will only contain skin scale; samples will be extracted with organic solvents and decontaminated with a 0.2 micron nylon filter prior to analysis on the LC-MS instrumentation.