PMS and PMDD are not the same thing

Most people who have severe premenstrual symptoms have been told, at some point, that they have PMS. Some of them do. A smaller group — somewhere around 3 to 8 percent of people who menstruate — have premenstrual dysphoric disorder, which is a different diagnosis with different treatment and a very different impact.

The distinction is worth caring about because PMDD responds well to specific treatments that are rarely offered to someone labelled with PMS.

What PMS looks like

Premenstrual syndrome covers physical and emotional symptoms in the luteal phase that resolve once bleeding starts. Bloating, breast tenderness, headaches, fatigue, irritability, low mood, food cravings, poor sleep.

It is extremely common — the majority of people notice something — and for most it is a nuisance rather than a crisis. The defining feature is timing, not severity: symptoms appear in the second half of the cycle and go away with the period. The luteal phase explains the physiology behind it.

What PMDD looks like

PMDD is in the DSM as a depressive disorder, and the criteria are specific. During most cycles, in the final week before bleeding, at least five symptoms are present, and at least one of them must be a core mood symptom:

• Marked mood swings, sudden sadness, or acute sensitivity to rejection
• Marked irritability or anger, often with increased interpersonal conflict
• Marked depressed mood, hopelessness, or self-critical thoughts
• Marked anxiety, tension, or feeling on edge

Plus additional symptoms which may include loss of interest, difficulty concentrating, fatigue, appetite change, sleep disturbance, a sense of being overwhelmed or out of control, and physical symptoms.

Two further requirements matter enormously and are frequently skipped. The symptoms must cause significant distress or interference with work, relationships or usual activities. And they must remit within a few days of bleeding starting and be absent in the week after the period.

That remission requirement is the hinge of the whole diagnosis.

The difference in practice

PMS is "I'm snappy and my jeans don't fit for a week."

PMDD is "for five days a month I am a different person, I believe things about myself and my relationships that I do not believe at any other time, and afterwards I have to repair the damage." Many people with PMDD describe knowing intellectually that it is the cycle and being entirely unable to act on that knowledge in the moment. Suicidal ideation is part of the picture for a substantial minority, and it is the reason this diagnosis matters rather than being a matter of labels.

Why the tracking requirement is not bureaucratic

You cannot diagnose PMDD from a blood test. Hormone levels in people with PMDD are typically normal — the difference is in how the brain responds to normal fluctuation, probably through sensitivity to allopregnanolone at GABA-A receptors.

So the diagnosis rests entirely on prospective daily ratings across at least two cycles. Prospective means recorded as you go, not remembered afterwards.

This is not a formality, and the reason is uncomfortable: retrospective recall is unreliable in a specific direction. People asked to remember their premenstrual weeks systematically over-attribute bad days to the cycle, and a meaningful proportion of people who are certain they have PMDD turn out, on daily tracking, to have symptoms that do not remit after their period. That does not mean nothing is wrong. It usually means an underlying mood or anxiety disorder that worsens premenstrually — premenstrual exacerbation — which is common and needs continuous treatment rather than cycle-timed treatment.

Getting that distinction right changes the prescription. It is the single most consequential reason to track.

What treatment looks like

For PMDD, the first-line options have decent evidence:

SSRIs. They work differently here than in depression — often within a day or two rather than weeks, which is why intermittent dosing during the luteal phase only is a recognised option alongside continuous dosing. That fast response is itself evidence that a different mechanism is involved.

Ovulation suppression. Combined hormonal contraception taken continuously, so there is no hormone-free interval and no cyclical fluctuation. Some formulations have better evidence than others. Birth control and mood is worth reading first, because hormonal contraception helps some people substantially and makes others worse.

Cognitive behavioural therapy has evidence, particularly for the interpersonal fallout.

For milder PMS: exercise, sleep, reducing alcohol — alcohol is a specific problem in the luteal phase — and calcium supplementation have some support. The evidence for most other supplements marketed for PMS is weak.

Practical first step

Before any appointment, track daily for two full cycles. Rate mood, irritability, anxiety and physical symptoms each day, whether or not it feels like a symptomatic day, and note where you are in your cycle. The days you rate as fine are as diagnostically important as the days you do not, because remission is the criterion.

This is precisely what Naked is designed to make effortless rather than a chore you abandon in week two — daily logging that lines up against your cycle automatically, so what you take to a doctor is two cycles of prospective data instead of a description.

Turning up with that record is often the difference between leaving with a diagnosis and leaving with a leaflet.