What is PMS (premenstrual syndrome)?
Premenstrual syndrome (PMS) is an umbrella term for the emotional and physical signs many women notice in the days before their period, which ease once it starts. Professional sources describe up to three in four women of reproductive age noticing at least one such sign at some point, usually mild.
In a smaller share, estimated at 3 to 8 percent, the emotional signs are severe enough to be called premenstrual dysphoric disorder (PMDD) – a separate, more severe form that a doctor or gynaecologist manages.
A symptom diary: why tracking several cycles is useful
Because PMS signs often look like signs of other conditions, doctors commonly recommend a diary for assessment: over two to three cycles, you note which signs appear, how strong they are, and when they occur relative to your period.
Such a record shows whether signs really appear in the second half of the cycle and ease after the period starts – that is the key to telling PMS apart from other causes of a similar pattern, such as a thyroid condition or a mood disorder unrelated to the cycle.
Everyday habits guidelines mention, and when to see a doctor
Among everyday habits women with PMS often try, guidelines mention a regular sleep schedule, regular movement, regular meals, and less caffeine, alcohol and salt in the days before a period. These are general pointers for everyday life, not instructions written for you specifically.
It is worth seeing a doctor or gynaecologist if signs get in the way of work, school or relationships every month, if emotional signs are very strong, or if you want to know what options are described for PMS and PMDD.
Frequently asked questions
What is PMS?
PMS (premenstrual syndrome) is a cluster of emotional and physical signs that appear in the days before a period and ease soon after it starts. At least one in three to four women of reproductive age notices these signs.
How do I know if it's PMS?
Guidelines (ACOG) describe PMS as at least one emotional and one physical sign that repeat for at least three cycles in a row, appear in the last five days before a period, and ease within four days of it starting. The self-check above shows whether your answers follow that pattern.
How is PMS different from pregnancy?
Some signs, such as tender breasts and tiredness, overlap. The main difference is that PMS signs ease once a period starts, while pregnancy signs do not. If a period is late, it is worth taking a pregnancy test.
What is the difference between PMS and PMDD?
PMDD (premenstrual dysphoric disorder) is a more severe form in which emotional signs, such as intense low mood or irritability, are strong enough to noticeably affect daily life. It is estimated to affect 3 to 8 percent of women of reproductive age and is managed by a doctor or gynaecologist.
How many days before a period do PMS signs start?
Usually in the last five days of the cycle, in the second half of the luteal phase, easing a few days after the period starts.
Sources
- ACOG – Premenstrual Syndrome (PMS)
- NHS – Pre-menstrual syndrome (PMS)
- Office on Women's Health – Premenstrual syndrome (PMS)
Updated: October 2026
An informational test, not a substitute for medical advice.