PMS and thyroid disease: how they interact

PMS and thyroid disease aren't the same thing, but they can look alike. Your thyroid makes hormones that help set your energy, mood, and metabolism. Your ovaries make estrogen and progesterone, which rise and fall through your cycle and drop sharply before your period.

These two systems don't cause each other, but their symptoms overlap enough to cause confusion. A 2020 clinical overview of PMS diagnosis lists hypothyroidism among the conditions doctors rule out before confirming PMS or PMDD, because low thyroid hormone can cause fatigue, low mood, and irregular periods that look like premenstrual symptoms ( [1]).

If you already have a thyroid diagnosis and your premenstrual weeks feel different from your usual baseline, that's a sign the two might be interacting, not proof that one is causing the other.

If your pattern feels more like PMDD than PMS, see PMDD and thyroid disease: how they interact and PMS vs PMDD, and when to see a doctor.

For some women, yes. This pattern has a name: premenstrual exacerbation, when an existing condition is present all month but flares in the week or two before a period and eases once it starts.

Thyroid disease can follow this pattern. If fatigue, low mood, or a racing heart are there most days but get noticeably worse before you bleed, that points to premenstrual exacerbation of your thyroid condition, not PMS causing a thyroid problem.

The research reviewed for this page doesn't include a thyroid-specific trial on this pattern, so this is based on how premenstrual exacerbation generally works, not a thyroid study. The distinction still matters:

Tracking both over a cycle or two is the clearest way to tell which one you're dealing with.

There isn't solid data, among the research reviewed here, on how many women have both PMS and a diagnosed thyroid condition at the same time.

What's clearer is that premenstrual symptoms alone are common. In one UK survey of working women, over 90% reported some premenstrual symptom, and 40% rated theirs as moderate or severe ( [2]). Thyroid disease, especially an underactive thyroid, is also common in women.

Because both are frequent on their own, some overlap is expected by chance, even without a direct link between the two. That survey also found moderate or severe premenstrual symptoms were tied to poorer general health and sleep, which can make an existing thyroid condition harder to manage day to day ( [2]).

If you have a diagnosed thyroid condition and notice your premenstrual symptoms have changed, raise it with your doctor rather than assuming it's just your thyroid or just PMS.

PMS and thyroid disease are treated separately, but your doctor needs to know about both.

Guideline-backed options for PMS include:

• Regular aerobic exercise, which systematic reviews of randomized trials found eased both physical and mood symptoms of PMS, including anxiety and anger ( [4], [5])
• Combined oral contraceptives, which a 2021 meta-analysis found reduced premenstrual depressive symptoms and overall symptom load in women with PMS or PMDD ( [3])
• SSRIs, which some doctors prescribe only in the two weeks before a period
• CBT

Thyroid disease is treated with thyroid hormone replacement for an underactive thyroid, or medication to lower thyroid hormone for an overactive one, decided and adjusted through blood tests by your doctor.

A doctor decides what's right for you. If you take thyroid medication and are also starting a treatment for PMS, mention both to your doctor so they can watch for interactions and check your thyroid levels if needed.

On a day when PMS and thyroid symptoms are both loud, fatigue and low mood can stack up fast. A few things that have evidence behind them, even though the trials weren't specific to thyroid disease:

• A short walk or other aerobic movement, which has eased both physical and mood symptoms of PMS across multiple trials ( [4], [5])
• Naming what feels like PMS, what feels like your thyroid, and what's the actual situation in front of you, so you're not fighting all three at once
• Writing down what happened before you respond to anyone, especially if you're more reactive than usual

Niyora is a PMS and PMDD support app. If you want help separating what happened from how you're feeling about it, Niyora's Moon lets you write down the moment, see it from another angle, calm down, and draft a reply you can hold for 20 minutes before you send it.

The clearest way to tell PMS, PMDD, premenstrual exacerbation, and thyroid disease apart is daily tracking, across at least two cycles ( [1]).

1. Write down your main symptoms every day, mood and physical, not just on the days they feel worse.
2. Note where you are in your cycle (day since your last period started).
3. Mark your thyroid medication doses and any missed ones.
4. After two cycles, look for the pattern: symptoms that show up only in the week or two before your period and ease within a few days of it starting point to PMS. Symptoms present most days, that worsen premenstrually but don't fully go away, point to premenstrual exacerbation of your thyroid condition.

A structured tool like the Daily Record of Severity of Problems (DRSP) chart makes this easier to do and easier to bring to an appointment. This quiz can also give you a quick first read on how much your premenstrual symptoms are affecting you.