If you have a pretty regular menstrual cycle, you know exactly when your body is telling you that your period is close. Pre-menstrual syndrome (PMS) can present itself in many ways from increased anxiety to changes in appetite. But if you have eczema, you might also notice an eczema flare before your period. “Your eczema sometimes can fluctuate with your hormone levels,” says Marisa Garshick, MD, a board-certified dermatologist in New York City. “We know that week before your period, when your estrogen level is lower, you may experience more dryness of the skin. And we know that when the skin is dry, it can predispose to a flare-up of eczema. We don’t warn patients about this but if somebody said they it, the rationale is there.” The available research on eczema flares in the week before a period is…