Every month, for a week or so, you barely recognise yourself. The tears arrive out of the blue, the world feels too loud, and then your period starts and the fog lifts. If that rhythm sounds familiar, this is for you.
⏱️ 8-minute read · Words by Chiara Ugozzoli · Updated June 2026
TLDR: Premenstrual syndrome (PMS = premenstrual syndrome) is the cluster of physical and emotional symptoms many women feel in the weeks before a period. Premenstrual dysphoric disorder (PMDD = premenstrual dysphoric disorder) is a much more intense, mood-dominated version that can seriously affect daily life. The clearest way to tell them apart is timing plus severity, and the gold-standard step is tracking your symptoms daily across at least two cycles before you see a doctor. Help exists, and you deserve it.
What exactly is PMS, and how common is it?
Let us start with the everyday version, because most women know it well. The NHS describes PMS as the symptoms women can experience in the weeks before their period, and it notes that most women have PMS at some point. So if you feel this monthly shift, you are in vast and ordinary company.
The common symptoms the NHS lists will ring true: mood swings, feeling depressed or irritable, feeling upset, anxious or emotional, tiredness or trouble sleeping, bloating or cramping, breast tenderness, headaches, spotty skin, greasy hair, and changes in appetite or food cravings. It is a broad mix of body and mood, and each woman’s pattern is her own and can shift from month to month.
The reassuring frame here is that PMS, while genuinely annoying, usually stays manageable with lifestyle steps and sits in the background of life while you carry on with your days. That distinction becomes the key to the next section.
So how is PMDD different from ordinary PMS?
Here is the heart of it. The NHS explains that a small number of women experience a more severe form of PMS known as PMDD, with symptoms similar to PMS but much more intense and capable of a far greater negative impact on everyday life. The physical symptoms can overlap, yet PMDD brings emotional symptoms to the foreground: the NHS names feeling very anxious, angry, depressed or suicidal.
The International Association for Premenstrual Disorders (IAPMD) frames PMDD as a cyclical, hormone-based mood disorder, with symptoms arising during the luteal phase (the premenstrual phase, the one-to-two weeks before your period) and subsiding within a few days of menstruation. Crucially, the IAPMD is clear that this happens even though hormone levels themselves sit in the normal range. PMDD reflects a heightened brain sensitivity to the natural rise and fall of oestrogen and progesterone. The IAPMD frames this as a sensitivity question, with the hormone levels themselves staying perfectly typical. That single fact lifts a lot of self-blame, because it means your experience is real and biological.
For a sense of scale, the IAPMD reports that roughly 1 in 20 people who menstruate experience these life-altering premenstrual symptoms. So PMDD is far less common than PMS, yet it touches a meaningful number of women, many of whom spend years searching for the right name.
Picture this. It is day 22 of your cycle. A tiny comment from a friend lands like a blow, you spend the evening convinced everyone would be better off elsewhere, and you feel utterly out of control. Three days later your period arrives, the storm clears completely, and you think, what was that? That clean on-off pattern, tied tightly to your cycle, is exactly the clue worth writing down.
How do I actually find out which one I have?
This is where you become the detective, and the method is beautifully simple. Both the NHS and specialists point to the same first move: track your symptoms. The NHS suggests keeping a diary of your symptoms for at least 2 menstrual cycles and taking it to a GP (general practitioner, a family doctor) appointment.
The IAPMD goes a step further on why this matters so much. Because blood, hormone and saliva tests currently stay unable to confirm PMDD, daily symptom tracking across at least two menstrual cycles remains the only current method for diagnosis. The IAPMD highlights a clinically validated tool, the Daily Record of Severity of Problems (DRSP = Daily Record of Severity of Problems), used by clinicians and researchers, which helps you see your pattern clearly and advocate for the right care.
What you are looking for in that record is the timing. In PMDD, symptoms cluster in the luteal phase and then ease within days of your period beginning. That cyclical signature is what marks it apart from a mood condition that runs steadily all month, which is why a doctor relies on your tracked record to tell them apart. Your two cycles of notes become the most useful thing you can carry into the room.
What help is out there once I know?
Plenty, and this is the part that deserves emphasis. For PMS, the NHS suggests everyday steps first: exercising regularly, eating a healthy balanced diet with smaller meals every 2 to 3 hours if that suits you, getting plenty of sleep, easing stress through yoga or meditation, and using painkillers such as ibuprofen or paracetamol for the aches.
When symptoms affect daily life or lifestyle changes have done as much as they can, the NHS advises seeing a GP, who may recommend treatments including hormonal medicine such as the combined contraceptive pill, cognitive behavioural therapy (CBT = cognitive behavioural therapy), or antidepressants. If symptoms persist, a referral to a specialist such as a gynaecologist, psychiatrist or counsellor may follow. The same pathways apply to the more severe PMDD picture, with care tailored to how intense the symptoms are.
One safety point sits above everything else. The NHS is explicit that if you have symptoms of PMDD and are feeling suicidal, this needs immediate help: call 999 or go to A&E. Please treat those feelings as the emergency they are, and reach for support straight away. You matter enormously, and that storm, however total it feels, will pass with your period and with the right care around you.
Try this tonight: Open a fresh note in your phone or a paper diary and write today’s date along with where you are in your cycle if you know it. Each evening for the next two cycles, jot a quick line on your mood, energy and any physical symptoms, plus a 1-to-10 number for how intense it felt. When you spot the pattern, book a GP appointment and bring it. That little record turns a vague monthly struggle into clear, named evidence a doctor can act on.
The gentle takeaway
If the days before your period feel like a different person steps into your life, you are sensing something genuine, and you deserve language for it. PMS is the common, usually manageable monthly shift that most women know. PMDD is a more intense, mood-led version tied tightly to the luteal phase, driven by a sensitive brain response to normal hormone changes, a sensitivity that sits entirely outside any fault of yours. The way to tell which one you are living with is to track daily across at least two cycles and take that record to a doctor. Help is real, from lifestyle steps to talking therapies to medical options, and urgent support stands ready if dark feelings ever take hold. Start with tonight’s note. Naming the pattern is the first kind thing you can do for yourself.
PrettyWell is a women’s lifestyle and wellbeing magazine. This article shares general information and wellbeing perspectives to help you ask better questions and feel more in charge; for anything about your own health, please speak with a qualified healthcare professional.
References
- NHS. PMS (premenstrual syndrome). https://www.nhs.uk/conditions/pre-menstrual-syndrome/
- International Association for Premenstrual Disorders (IAPMD). What is PMDD? https://www.iapmd.org/pmdd
