Hot Flashes During Your Period: Is It Normal and What It Means

Hot flashes before or during your period are common, especially if you also get premenstrual symptoms. They usually track the drop in estrogen at the end of the cycle. New flashes alongside cycles that are changing length can be an early perimenopause sign worth testing.

Published

April 23, 2026

Last updated

October 13, 2026

Read time

7 min read

Medically reviewed by

Rhonda Collins, FNP-C

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Yes, hot flashes before or during your period are common. In one study, more than 4 in 5 women with premenstrual syndrome (PMS) reported episodes of chills and sweats like menopausal hot flashes during a single cycle, and so did about 4 in 10 women with no cycle symptoms at all. They usually follow the fall in estrogen at the end of the cycle. Two things change what they mean: your age and whether your cycles are changing length.

Why Hot Flashes Happen Around Your Period

Period-linked hot flashes come from the same brain temperature system as menopausal flashes. They come and go with the cycle instead of staying.

• Estrogen falls at the end of each cycle. Estrogen and progesterone drop in the days before your period and stay low as bleeding starts.
• That narrows your heat tolerance. In menopause research, a hot flash is a heat-release response set off by a very small rise in core body temperature. Lower estrogen is one reason the comfortable temperature range shrinks, so a small change in heat tips you into flushing and sweating.
• The flash fades as estrogen climbs again. As the next cycle gets going, estrogen rises and the flashes usually ease.
• Triggers add to it. Stress, a warm room, alcohol and fatigue lower the threshold further. In women with regular cycles who had hot flashes, stress was the most common thing that made them worse.

Hot Flashes Before vs During Your Period

Both are normal patterns, and many women get both. Flashes are often strongest in the days before bleeding and can carry into the first days of the period.

• Before your period. In a Fertility and Sterility study of women aged 18 to 45, episodes of chills and sweats rose and fell with daily premenstrual symptom scores. Women with PMS averaged about 6 episodes per cycle and women with chronic cycle-related symptoms about 10, compared with about 1 in women without cycle symptoms.
• During your period. In a study of young women with regular cycles and hot flashes, 68% said their flashes got worse before their period and 61% said they got worse during it.
• At night. The same pattern at night shows up as sweats. See night sweats during your period for what changes when it happens in your sleep.

Hot Flashes With Regular Periods

Regular periods do not rule out hot flashes. In a study of 38 women aged 18 to 40 with regular monthly cycles, normal FSH, estradiol and prolactin, and no hormonal birth control, most had hot flashes every day and many had sweating with them. Anxiety and low vitamin D, not menopause hormone levels, were the factors linked to the flashes. That study was small and recruited from one hospital in Jordan, so treat it as a sign that these flashes exist, not as a full list of causes.

If your cycles are regular and the flashes cluster around your period, the cycle itself is the most likely explanation. If they happen at random times, look at other causes first.

In Your 30s and When Perimenopause Flashes Start

Perimenopause hot flashes can start before your periods change, but they become much more likely once your cycles do.

• The STRAW+10 staging system describes the early menopausal transition as cycle lengths that keep differing by 7 days or more from one cycle to the next. It says hot flashes are likely in the late transition, once you go 60 days or more between periods, and most likely in the first years after the final period.
• Some women start earlier. In the SWAN study of more than 3,000 US women, some first reported frequent hot flashes while still premenopausal or in the early transition. Those women had the longest-lasting flashes overall.
• In your 30s, period-linked flashes with no change in your cycle most likely reflect the normal cycle pattern above. Flashes plus real cycle change in the late 30s are worth testing. See hot flashes in your 30s for the causes most common at that age.

Other Causes to Rule Out

Flashes that do not follow your cycle point away from it. Cleveland Clinic names thyroid disorders, viral infections and certain medicines as causes of hot flashes outside menopause, and stress as a factor that makes them worse.

• Thyroid problems. An overactive thyroid causes heat intolerance and sweating at any point in the cycle. A TSH test is the usual first check.
• Infection or fever. A viral illness such as the flu can cause flushing. A flash that comes with a measured fever points to an illness rather than your cycle.
• Medicines. Some prescription medicines cause flushing or sweating. Note when a new medicine started relative to the flashes.
• Stress and anxiety. Flashes that follow stressful events rather than cycle days fit a stress pattern. See hot flashes with anxiety.

How to Track Hot Flashes Against Your Cycle

A cycle-day log is the most useful thing you can bring to a test or appointment. The Fertility and Sterility study above measured cycle-linked flashes the same way, with a daily symptom calendar kept across a full cycle.

1. Count day 1 as the first day of full bleeding. Start a new count each period.
2. Log every flash with the cycle day, the time, how strong it felt from 0 to 10, and whether it woke you.
3. Note likely triggers that day: alcohol, a warm room, a stressful event, illness or fever, or a new medicine.
4. Record each cycle’s length. That is the number of days from one day 1 to the next.
5. Keep it for at least two cycles, then read the pattern.

What the log tells you:

• Flashes bunched in the days before and the first days of your period, every cycle: a cyclical pattern that fits the estrogen drop.
• Flashes plus cycle lengths that keep differing by 7 days or more: the early-transition pattern in STRAW+10. Test FSH and estradiol.
• Flashes spread across the cycle with no link to cycle day: look at thyroid, medicines, stress and illness first.

Which Hormone Tests to Take, and When

Test FSH and estradiol early in the cycle, on cycle days 2 to 5. That is the early follicular window that STRAW+10 uses to judge FSH, and the Mito product pages note that these tests are usually drawn around day 3. Write down the cycle day of the draw, because both hormones change across the cycle.

• LH, FSH, and Estradiol (E2) Panel: the best single choice for cycle-linked flashes. It reads FSH and estradiol together with LH, and the pattern is what matters. High FSH and LH with low estradiol points to the ovaries, as in perimenopause.
• Follicle-Stimulating Hormone (FSH) Blood Test or Estradiol (E2) Blood Test on their own, if you only need one marker or are repeating one.
• Thyroid-Stimulating Hormone (TSH) Blood Test: for flashes that do not follow your cycle.
• At-Home Women’s Hormone Test Kit: an at-home option that adds progesterone, prolactin, testosterone, DHEA-S and free T4 to FSH, LH and estradiol. Record your cycle day when you collect. It includes free T4 but not TSH, so it is not a full thyroid check.

How to read the results:

• One normal FSH does not rule out perimenopause. STRAW+10 notes that a single FSH or estradiol result can be misleading in the transition, and a repeat test is often needed.
• Hormonal birth control, fertility medicines and hormone therapy change all three results. Note anything you take.
• Estradiol is normally near its low point on days 2 to 5. Compare it with the follicular-phase range on your report, not the mid-cycle range, and read it alongside FSH and your cycle history.

When to See a Clinician

Most cycle-linked flashes do not need urgent care. Book an appointment with your doctor if:

• flashes come with a fever, drenching sweats, or weight loss you cannot explain;
• you are under 40 and your periods have become irregular or stopped, since that can be a sign of primary ovarian insufficiency or high prolactin;
• flashes are new, frequent and not tied to your cycle;
• flashes or sweats are disrupting your sleep or daily life, whatever the cause.

Bring your cycle-day log and any hormone or thyroid results.

Related Reads

• Perimenopause: Estradiol and Progesterone Symptoms
• Female Hormone Testing: A Guide for Women at Every Stage
• Hormone Imbalance: Symptoms, Testing, and What Your Body May Be Telling You

References

• Hahn PM, Wong J, Reid RL. Menopausal-like hot flashes reported in women of reproductive age. Fertility and Sterility, 1998
• Sindiani AM, Alkhatatbeh MJ, Abdul-Razzak KK. Hot flashes in adolescence and young adult females: a link to vitamin D and calcium. Medical Archives, 2022
• Harlow SD, et al. Executive summary of the Stages of Reproductive Aging Workshop + 10 (STRAW+10). Climacteric, 2012
• Avis NE, et al. Duration of menopausal vasomotor symptoms over the menopause transition (SWAN). JAMA Internal Medicine, 2015
• Freedman RR. Menopausal hot flashes: mechanisms, endocrinology, treatment. Journal of Steroid Biochemistry and Molecular Biology, 2014
• Cleveland Clinic, Hot Flashes

Frequently asked questions

Is it possible to have hot flashes while having a regular period?

Yes. Hot flashes are not limited to women whose periods have stopped or become irregular. In a study of 38 women aged 18 to 40 with regular monthly cycles and normal FSH, estradiol and prolactin, most had hot flashes every day, and stress and the days before a period were the two most common things that made them worse. In those women, anxiety and low vitamin D, not menopause hormones, were the factors linked to flashes.

At what stage of perimenopause do hot flashes start?

They can start at any stage. The STRAW+10 staging system says hot flashes are likely in the late menopausal transition, when you start going 60 days or more between periods, and most likely in the first years after the final period. But in the large SWAN study, some women first reported frequent hot flashes while still having regular periods or in the early transition, when cycle lengths first start to vary by 7 days or more from one cycle to the next.

Can you get hot flashes right before your period starts?

Yes. Flashes and sweats are often worst in the days before bleeding, when estrogen and progesterone fall, and they can continue into the first days of the period. In a study of women with premenstrual syndrome, episodes of chills and sweats rose and fell with their daily premenstrual symptom scores.

Do hot flashes during your period mean low estrogen?

Not on their own. Estrogen is normally at its lowest around the start of a period, so a flash at that point reflects a normal drop rather than a deficiency. A single estradiol result also varies a lot from day to day around perimenopause, which is why it is read together with FSH, your cycle day and your cycle history.

When is the best time in my cycle to test FSH and estradiol?

Early in the cycle, on days 2 to 5, counting the first day of full bleeding as day 1. That is the window the STRAW+10 staging criteria use for FSH. Because FSH and estradiol can swing from cycle to cycle in perimenopause, one normal result does not rule it out, and a repeat test is often needed.