Roughly days 1 to 5

Menstrual phase

Your period. Hormone levels are at their lowest, and many people want warmth, rest, and less fuss.

What's happening

The menstrual phase starts on the first day of bleeding. Estrogen and progesterone are low, and the uterine lining sheds over three to seven days. Cramps, low energy, and lower-back aches are common, especially in the first couple of days.

What many people find helpful

Period essentials

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See a doctor if your cramps keep you from normal activities, if you soak through a pad or tampon every hour, or if your periods suddenly change.

Next up: follicular phase