Premenstrual Syndrome (PMS)

Premenstrual syndrome, or PMS, is the set of physical and emotional changes that appear in the second half of the menstrual cycle and settle within a few days of a period starting. Premenstrual dysphoric disorder, or PMDD, is a more severe form in which mood symptoms are strong enough to interfere with work, school, relationships or daily life. Both follow the hormonal rhythm of the cycle, and both stop when menstruation stops.

What PMS and PMDD are, and what they are not

The key feature is timing, not the symptom list. Cramps, low mood or irritability on their own do not tell a clinician much. What points to PMS or PMDD is that symptoms build in the days before a period and clear within a few days of it arriving, cycle after cycle. If the same symptoms carry on all month, that pattern points to a different condition that needs its own assessment.

PMDD is also not simply a heavier version of a normal week. The Canadian Medical Association Journal describes it as requiring five or more symptoms, including at least one mood symptom, tracked across two or more cycles. That threshold exists because PMDD disrupts daily functioning, and because it is a recognised clinical condition rather than a matter of personality or willpower.

Signs and symptoms

• Low mood, tearfulness or a sense of hopelessness in the days before a period
• Irritability, anger or sudden mood changes
• Anxiety, or feeling on edge
• Trouble concentrating, or feeling mentally foggy
• Sleep changes, either sleeping much more or much less
• Tender breasts, bloating, headaches, cramps and joint or muscle aches
• Changes in appetite or food cravings

Which symptoms show up, and how strongly, differs from person to person and can change across the years. In the Toronto study behind the figure above, cramps and bloating were the most commonly reported symptoms, followed by mood swings.

What raises the risk

Some things cannot be changed:

• Having menstrual cycles, since symptoms are tied to the hormonal rhythm of the cycle
• A personal or family history of depression, anxiety or postpartum mood conditions
• Individual differences in how the brain responds to normal hormone shifts
• Age, since symptoms often become more noticeable in the late reproductive years

Others can often be worked on, usually with support from a health care team:

• High or ongoing stress load
• Smoking
• Sleep disruption, low physical activity, and heavy alcohol or caffeine use, which some people find make symptoms harder to manage

How PMS and PMDD are diagnosed in Canada

There is no blood test for either condition. Clinicians in Canada ask you to record your symptoms every day for at least two menstrual cycles, because the timing of symptoms relative to your period is what separates these conditions from mood or physical conditions that continue all month. The Canadian Medical Association Journal notes that looking back over past cycles from memory is unreliable, which is why day-by-day tracking is used instead. A history, a physical examination and sometimes blood work may be used to rule out other explanations such as thyroid conditions or anaemia.

Treatment and day-to-day management

Clinical research for Premenstrual Syndrome (PMS) is enrolling. See the current studies ↓

Care in Canada is aimed at the symptoms that affect you most, and at the part of the cycle when they appear. Depending on your situation and what matters to you, a health care team may discuss:

• Selective serotonin reuptake inhibitors and related serotonergic antidepressants, taken either continuously or only in the second half of the cycle
• Combined hormonal contraception, including drospirenone-containing formulations
• Gonadotropin-releasing hormone agonists with hormone add-back, described in the Canadian literature for severe or treatment-resistant PMDD
• Non-prescription pain relief and anti-inflammatory medicines for physical symptoms such as cramps and headaches
• Cognitive behavioural therapy, and changes to exercise, sleep routines, caffeine and alcohol

What suits one person will not suit another. Which of these applies to you, if any, is a decision for you and your own clinician, and this page is not a recommendation about any of them.

When to talk to a doctor

• Speak with a clinician if premenstrual symptoms regularly interfere with work, school, caregiving or relationships, or if over-the-counter measures are not enough.
• Seek care promptly if you have thoughts of suicide or self-harm at any point in your cycle. In Canada you can call or text 988, the Suicide Crisis Helpline, at any time.
• Book an appointment if symptoms do not settle within a few days of your period starting, or continue all month, since that pattern points to a different condition that needs its own assessment.

Why clinical research matters for PMS and PMDD

Researchers still do not know why a minority of people are highly sensitive to ordinary cyclical hormone changes while most are not, and there is no biological test that identifies PMDD. Canada has no national prevalence estimate for either condition, and little Canadian data on how long people wait for a diagnosis or how many receive care: the closest Canadian figure comes from a single study of women aged 20 to 29 in one city. Trials under way are examining compounds that target neurosteroid pathways, antidepressant strategies given continuously or only in the luteal phase, hormonal suppression approaches, and digital cycle-tracking tools to support day-by-day diagnosis.

Clinical studies are how those questions get answered. Taking part is voluntary, you give informed consent before anything begins, and you can stop at any time without affecting the care you get from your own doctor. Joining a study does not mean giving up your current treatment, and no one can tell in advance whether a study will help you personally.

Learn more from Canadian sources

• Your Period, Society of Obstetricians and Gynaecologists of Canada: premenstrual syndrome
• Sex and U, Society of Obstetricians and Gynaecologists of Canada
• Canadian Medical Association Journal: premenstrual dysphoric disorder review
• Action Canada for Sexual Health and Rights: Access Line and Sexual Health Hub