What is PMS? Premenstrual syndrome, explained

PMS stands for premenstrual syndrome. Premenstrual means before your period, the stretch of your cycle after ovulation and before bleeding starts. PMS is the name for physical and emotional symptoms that show up in that window and ease once your period begins.

You might also see it called PMT, premenstrual tension, in older medical writing. The name has changed over the decades, but what it describes hasn't. These are symptoms tied to a specific part of your cycle, not a mood you chose or a trait you have.

PMS covers a broad cluster of symptoms, physical and emotional, that rise and fall with your hormones rather than point to a single cause. Most people with periods notice some version of it at some point, even if most months it's mild enough to barely register.

PMS is caused by the normal hormonal shift that follows ovulation. Once an egg releases, estrogen and progesterone rise through the luteal phase, then fall sharply in the days before your period if you haven't conceived. That drop affects brain chemicals, including serotonin, and that's where the mood and energy symptoms come from.

Your hormone levels themselves are usually typical. What differs between people is how sensitive the brain is to that drop, and sensitivity to the same hormonal swing varies a lot from person to person.

Genetics, stress, poor sleep and underlying mood conditions can all make symptoms more noticeable in a given month, even though the hormonal trigger stays the same. For a closer look at the mechanism, read what causes PMS.

PMS usually starts one to two weeks before your period, during the luteal phase, and eases within a day or two of your period starting. For most people that's a window of roughly 5 to 11 days (NHS, 2022), though it can run shorter or longer.

Timing varies by cycle and by person. Stress, poor sleep or a shorter-than-usual cycle can shift when symptoms begin. Some people notice a pattern only in the final two or three days before bleeding, others feel it building for closer to two weeks.

Tracking a few cycles is the easiest way to find your own pattern. For specifics on timing, read when does PMS start.

PMS affects an estimated 30% of women of reproductive age (ACOG, 2023), though prevalence estimates vary widely by population and measurement method, for example ranging from 8.6% to 65.8% among the athlete studies reviewed in a 2025 Biology of Sport meta-analysis. Most people get a mix of physical and emotional symptoms.

Physical symptoms:

• Bloating and breast tenderness
• Headaches
• Fatigue or low energy
• Joint or muscle aches
• Appetite changes or cravings
• Trouble sleeping

Emotional and cognitive symptoms:

• Irritability or a short fuse
• Mood swings
• Anxiety or feeling on edge
• Low mood or tearfulness
• Trouble concentrating
• Feeling overwhelmed by things that usually feel manageable

The mix and intensity shift from month to month and person to person. Mild bloating one cycle, a wave of irritability the next. What marks these as PMS rather than something else is the timing. They build in the week or two before your period and lift once it starts. If a symptom sits with you all month and only gets worse before your period, that's a different pattern, more on that next.

Most premenstrual symptoms are PMS, common and usually manageable, not severe enough to take over your week. PMDD is different. It's a diagnosis in the DSM-5-TR and ICD-11, requiring at least five symptoms in the week before your period, including one mood symptom such as rejection sensitivity, anger or anxiety, severe enough to disrupt your relationships or work.

There's a third pattern worth knowing about, premenstrual exacerbation. It's when an existing condition like depression, anxiety or ADHD is present all month but gets noticeably worse before your period. Around 60% of women with a mood disorder report this kind of flare (a 2021 review in Current Psychiatry Reports). Unlike PMDD, the underlying condition doesn't disappear after your period, it just quiets down.

If you're not sure which pattern fits you, two months of daily notes on your symptoms and their timing usually makes it clear. Read PMS vs PMDD, and when it's time to get checked for the full breakdown.

For milder PMS, small daily changes can help:

• Regular exercise
• Consistent sleep
• Cutting back on alcohol and caffeine
• Getting enough calcium and vitamin D

These won't make PMS disappear, but they take the edge off for many people.

For PMS severe enough to disrupt your week, a 2017 interdisciplinary consensus guideline from Switzerland lays out a treatment ladder that includes cognitive behavioral therapy, certain hormonal contraceptives, antidepressants and, in some cases, treatment that suppresses ovulation (Gynecological Endocrinology, 2017). Which option fits depends on your symptoms, your age and whether you're trying to conceive, and a doctor makes that call.

In the moment, what helps most is something small you can do right now. Niyora is a PMS and PMDD support app. Its Moon tool lets you write down what just happened, see it from another angle once you've cooled off, and draft a reply you can hold onto instead of sending something you'll regret. It also gives you an estimated window for your next PMS stretch, so the dip doesn't blindside you. For a fuller list of options, see PMS treatment: what actually helps.

If PMS is consistently taking over a week of good functioning, straining a relationship you want to keep, or interfering with work, it's worth getting checked.

Bring two months of daily notes on what you feel and when. That's the fastest way for a doctor to tell PMS apart from PMDD or premenstrual exacerbation.

Mention any existing diagnosis, like depression, anxiety or ADHD, since premenstrual exacerbation of those conditions needs a different treatment path than PMS or PMDD on their own. A doctor can also rule out conditions like thyroid problems that sometimes mimic PMS symptoms.

You don't need to wait until it feels unbearable to ask for help. If you want to see how your days compare to a typical PMS pattern, start with what you're feeling right now.