PMS vs PMDD — Key Differences
PMS and PMDD are both premenstrual conditions, but PMDD involves severe mood disruption that impairs daily life. Here's how to tell them apart and what to do about each.
Medical disclaimer
This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Dawn Phase is not a medical device. Always consult a qualified healthcare professional with questions about your health.
What causes it
Both PMS and PMDD are driven by sensitivity to the hormonal shifts of the late luteal phase — particularly the fall in oestrogen and progesterone. In PMDD, the brain's response to these shifts appears exaggerated, likely involving differences in GABA receptor sensitivity, serotonin signalling, or neurosteroid metabolism. The hormone levels themselves are typically normal; it's the neurological response to the changes that differs.
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Daily symptom tracking across at least two full cycles is the cornerstone of diagnosing both PMS and PMDD. Record the type and severity of each symptom and the cycle day it occurs on. A pattern of severe symptoms confined to the luteal phase (days 15–28) that resolve promptly with menstruation, and which impair functioning, meets the PMDD criteria. This record is also what your doctor will ask for.
When to see a doctor
See a doctor if premenstrual symptoms are causing significant distress or impairing work, relationships, or daily activities. PMDD is underdiagnosed — many women are treated for depression without the cyclical pattern being recognised. A symptom log is the most useful thing you can bring to the appointment.
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