Why do I get hot flashes during my period?

Bottom lineHot flashes during your period usually come from the sharp estrogen dip just before and during bleeding, which narrows the brain's temperature comfort zone; PMDD, thyroid problems, and early perimenopause (especially if you are 40 or older) are the other main explanations, so see a doctor if flashes are new, frequent, or come with other symptoms.

Hot flashes during your period are usually driven by the same mechanism as menopausal ones: a drop in estrogen. Estrogen falls sharply just before and during the first days of bleeding, and in some women that dip is enough to unsettle the brain's temperature control center, triggering sudden waves of heat, flushing, or sweating.

The estrogen dip

Your hypothalamus keeps your body within a temperature "comfort zone," and estrogen helps keep that zone wide. When estrogen drops around menstruation, the zone can narrow, so small triggers - a warm room, coffee, stress - set off a full heat-and-sweat response. For most women the flashes fade once bleeding is underway and estrogen starts climbing again.

Other causes worth considering

• PMDD or severe PMS - hormone-sensitive women can get flushing, night sweats, and mood symptoms clustered in the late luteal phase and early period
• Perimenopause - if you are 40 or older (occasionally late 30s), period-time hot flashes that are new, spreading to other cycle days, or arriving with irregular cycles and sleep problems may be the earliest sign of the transition
• Thyroid problems - an overactive thyroid causes heat intolerance and sweating at any cycle phase
• Fever, infection, medications, alcohol, and low blood sugar can all masquerade as cycle-linked flashes

What helps

Layered clothing, a cooler bedroom, limiting alcohol and caffeine around your period, and tracking exactly which cycle days the flashes hit. A clear pattern is useful evidence for your doctor.

When to see a doctor

See a clinician if hot flashes are new and you are over 40, happen throughout your cycle, come with palpitations, weight loss, or heat intolerance (thyroid signs), disturb sleep regularly, or arrive with drenching night sweats and fever.

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