PMS, explained simply
Your cycle, your hormones and your symptoms, one small step at a time and with plenty of pictures.
What is PMS?
PMS (premenstrual syndrome) is a set of physical and emotional changes that show up in the days before your period and fade once your period starts.
It's very common. About 3 in 4 women who get periods notice at least some PMS. For most, it's mild. For some, it gets in the way of work, school and relationships, and that deserves real attention.
Why does it happen?
Nobody knows the full answer yet. The best explanation is that after ovulation, the hormones estrogen and progesterone rise and then drop quickly. Some brains are extra sensitive to that drop, partly through a mood chemical called serotonin. Your hormones are usually normal. It's your sensitivity to the change that makes the difference.
Your cycle, in one picture
A "typical" cycle is about 28 days, but anywhere from 21 to 35 days is normal. Day 1 is the first day of bleeding.
🩸 Period (days 1–5)
The lining of the uterus sheds. Hormones are at their lowest. PMS usually fades now.
🌱 Follicular (days 6–13)
Estrogen climbs. Many women feel more energy and a brighter mood.
✨ Ovulation (around day 14)
An egg is released. Estrogen peaks and then dips.
🍂 Luteal (days 15–28)
Progesterone rises, then both hormones fall if there's no pregnancy. That fall is when PMS tends to appear.
Common symptoms
There are more than 100 possible symptoms. Most women only get a few, and they can change from month to month.
In your heart and mind
In your body
PMS, PMDD and PME: what's the difference?
They're related, but they aren't the same. Knowing which one fits you helps you find the right kind of help.
| PMS | PMDD | PME | |
|---|---|---|---|
| What it is | Premenstrual syndrome: mild to moderate symptoms before a period | Premenstrual dysphoric disorder: severe mood symptoms before a period | Premenstrual exacerbation: an ongoing condition gets worse before a period |
| Main feeling | Uncomfortable, moody, bloated | Deep sadness, rage, anxiety, hopelessness | Your usual symptoms (for example of depression, anxiety, ADHD or migraine) flare up |
| All month? | No. Clears after the period starts | No. Clears after the period starts | Yes, the condition is there all month and just worsens before the period |
| How common | Very common | About 1 in 20 | Common in people with other conditions |
| Where to start | Lifestyle changes, tracking, simple remedies | See a doctor. Effective treatments exist. | See a doctor about the main condition |
When should I see a doctor?
- Your symptoms make it hard to work, study, parent or keep up relationships.
- Your mood drops sharply every month, or you have thoughts of hurting yourself.
- Lifestyle changes haven't helped after 2–3 cycles.
- Your symptoms don't go away after your period starts.
- Your periods are very painful, very heavy or irregular.
Bring your symptom tracking. It is the single most useful thing you can show a doctor.
Sources we learned from
International Association for Premenstrual Disorders (iapmd.org) · National Association for Premenstrual Syndromes, UK (pms.org.uk) · HealthyWomen (healthywomen.org) · U.S. Office on Women's Health (womenshealth.gov) · American College of Obstetricians and Gynecologists (acog.org) · Mayo Clinic (mayoclinic.org)