Mood swings before your period: PMS, PMDD or something else?

Every month it seems to happen. A few days before your period, you snap at people you love. You cry over small things, or you feel a heavy dread that has no clear reason. Then the period comes, and you feel like yourself again. Or maybe you do not feel better at all, and you cannot tell whether your cycle has anything to do with it.

Both experiences are common, and both deserve to be taken seriously. This article explains how premenstrual mood changes (PMS), a severe form called PMDD, a worsening of depression or anxiety before your period, and problems unrelated to your cycle can be told apart. It cannot tell you which one you have. Only a doctor or mental health professional can do that.

Why the timing matters

The days from ovulation until your next period are called the luteal phase. Premenstrual symptoms belong to that stretch. MedlinePlus describes it as a group of physical and emotional symptoms that start one to two weeks before your period, and says they should end within about four days after your period starts to count as PMS.

Doctors look at when symptoms start and when they stop. A pattern that returns before each period and then clears is one clue. A pattern that does not follow your cycle is another.

PMS: common and often mild to moderate

The NHS says most women have PMS at some point. Common symptoms include mood swings, feeling low or irritable, anxiety, tiredness or poor sleep, bloating, breast tenderness, headaches and changes in appetite. Symptoms can vary from month to month. For many people, PMS is a nuisance. For others it affects work and relationships, and that is a good reason to see a doctor.

PMDD: a more severe pattern

Premenstrual dysphoric disorder (PMDD) is a severe form of the premenstrual pattern. The mood symptoms are stronger, such as intense anxiety, anger, deep sadness or hopelessness, and they get in the way of daily life. The NHS notes that PMDD symptoms can include feeling suicidal.

The American Psychiatric Association's DSM-5 criteria, as reproduced in a 2021 published review (Osborn and colleagues), describe it like this. In most cycles, at least five symptoms appear in the final week before the period. They begin to improve within a few days after the period starts, and are minimal or absent in the week after. At least one of them is a mood symptom: mood swings, irritability or anger, low mood or hopelessness, or anxiety or tension. The symptoms cause real distress or get in the way of work, studies or relationships.

It is less common than PMS. A 2024 review pooling 44 studies (Reilly and colleagues, Journal of Affective Disorders) found that about 3.2% of women met criteria when the diagnosis was confirmed with daily tracking, and about 7.7% when it was only provisional. The range was wide, which is why numbers differ between sources.

When depression or anxiety is the main story

Sometimes the problem is not limited to the days before your period. There are two other common patterns:

• Low mood or anxiety that is there all month, with no clear link to your cycle. This may be depression or an anxiety condition on its own.
• Low mood or anxiety that is present all month and gets noticeably worse before your period. This is called premenstrual exacerbation.

Womenshealth.gov says depression and anxiety disorders are the most common overlap with PMS, and they may worsen before or during a period. A 2024 review in Frontiers in Psychiatry (Lin and colleagues) explains the key difference. In PMDD and PMS, symptoms clear in the weeks after the period. In premenstrual exacerbation, the symptoms of the existing condition continue through the whole cycle and worsen before the period. PMDD can also exist alongside depression or anxiety, so the picture can be mixed.

Why tracking for two cycles is the standard

Looking back, it is easy to blame the cycle for a bad week or to forget a good one. That is why the Reilly 2024 review states that a confirmed PMDD diagnosis needs prospective monitoring of symptoms over two cycles, otherwise the diagnosis is only provisional. Prospective means you record it day by day as it happens. The DSM-5 criteria say the pattern should be confirmed by daily ratings over at least two symptomatic cycles, though a provisional diagnosis can be made before that. The NHS also advises keeping a symptom diary for at least two menstrual cycles and taking it to your doctor. Womenshealth.gov suggests a calendar or phone app.

A rating form called the Daily Record of Severity of Problems is the most commonly used tool for this, according to an international consensus paper (ISPMD). You do not need that exact form to start. A simple note each evening is useful:

• The day your period starts and ends
• Your mood, anxiety, irritability and energy, each rated from 0 (none) to 3 (severe)
• Sleep, appetite and body symptoms such as bloating or headaches
• Whether the day affected work, family or plans

The thing to look for is whether you have a clearly better week after your period, when symptoms are minimal or absent. That better window is what points towards a premenstrual pattern. If you have no good week at all, that is equally important information for your doctor.

Other causes a doctor may check

Some physical conditions and medicines can look like a premenstrual mood problem. DSM-5 criteria say the symptoms must not be due to a medication, a substance or another medical condition. A clinical summary on PsychDB lists anaemia, an underactive thyroid, endometriosis and other conditions that can mimic PMDD. Healthdirect says your doctor may suggest blood tests to check thyroid function, and may refer you to a gynaecologist if your periods are irregular.

Two more points are worth raising with your doctor. First, a clinical summary on PsychDB notes that mood symptoms starting with hormonal contraception and settling after stopping it point to a medication effect rather than PMDD. Do not stop or change a contraceptive on your own. Talk to your doctor. Second, the same summary notes symptoms can worsen as menopause approaches, so tell your doctor your age and any change in your periods.

Whatever the cause, if sleep has been poor, or you have had a stressful month, mention that too. It all helps build the picture.

How a doctor assesses this

There is no single blood test or scan for PMS or PMDD. MedlinePlus and Womenshealth.gov both say the doctor relies on your description of symptoms, when they happen and how they affect your life. Expect questions about your cycle and your mood, and bring your diary. Your doctor may also do tests to rule out other causes. If symptoms are severe or do not respond to first steps, you may be referred to a gynaecologist or psychiatrist.

What helps while you find out

Whatever the final answer, the NHS lists a few steps many people find useful: regular exercise, a balanced diet, enough sleep, stress-reducing practices such as yoga or meditation, avoiding smoking and limiting alcohol. A GP may also suggest CBT, hormonal medicines or antidepressants if symptoms stay troublesome. These are decisions to make with your doctor, not alone.

In India, periods are still treated as something private or embarrassing in many homes. A 2021 meta-analysis of Indian studies (Dutta and Sharma, Health Promotion Perspectives) noted that awareness of premenstrual disorders and help-seeking for them has been low, partly because menstruation is taboo and because of traditional gender roles. If you have been told to put up with it, you are not alone, and you are allowed to ask for help.