PMS and PMDD both cause symptoms in the days before your period, but they differ in severity. PMS (premenstrual syndrome) is common and usually manageable. PMDD (premenstrual dysphoric disorder) is a severe condition that affects around 1 in 20 people who have periods, with mood symptoms strong enough to disrupt work, relationships and daily life.
What PMS and PMDD have in common
Both follow the same timing. Symptoms start in the luteal phase, the one or two weeks after ovulation, and ease within a few days of your period starting. In the week after your period there are few or no symptoms.
This on-off pattern is what separates premenstrual conditions from symptoms that last all month. You can read more about this part of the cycle on our luteal phase page.
The key differences
| PMS | PMDD | |
|---|---|---|
| How common | Most people with periods have some symptoms | Around 1 in 20 |
| Main symptoms | Bloating, breast tenderness, tiredness, mild mood changes | Severe depression, anxiety, anger or mood swings |
| Impact | Uncomfortable, daily life goes on | Disrupts work, relationships and daily life |
| Diagnosis | Based on your symptom pattern | Daily symptom records over at least two cycles |
Why PMDD happens
People with PMDD usually have normal hormone levels. Research suggests the brain reacts unusually strongly to the normal rise and fall of oestrogen and progesterone after ovulation. That is why PMDD is not a sign that something is wrong with your hormones, and why blood tests alone cannot diagnose it.
PMDD or premenstrual exacerbation?
Some people have a condition such as depression or anxiety that gets worse before their period. This is called premenstrual exacerbation (PME). The difference matters: with PMDD, symptoms almost disappear after the period, while with PME they are present all month and only get stronger before bleeding. Daily records help a professional tell the two apart.
How PMDD is diagnosed
A diagnosis is based on symptoms you record every day for at least two cycles, not on memory. For each day, note:
- Your mood: sadness, anxiety, irritability, anger, mood swings.
- Physical symptoms: bloating, breast tenderness, headaches, sleep changes.
- How much the symptoms affected work, study or relationships.
- The cycle day and when your period started.
Bring these records to a GP or gynaecologist. Effective treatments exist, and a professional can explain which options fit you. Our guide to the questions your doctor may ask helps you prepare.
When to get help straight away
If you have thoughts of harming yourself, do not wait for the next cycle. Contact a doctor, an emergency number or a crisis line now. The International Association for Premenstrual Disorders (IAPMD) also offers peer support and information.
Tracking premenstrual symptoms in Bloom Private
Bloom Private lets you log more than 60 physical and emotional symptoms on each cycle day, with your records stored on your iPhone and no account.
After a few cycles you can export a PDF report to bring to your appointment (basic PDF free, full report with Premium). Bloom Private is a tracking tool, not a medical device, and it does not diagnose PMDD. Always consult a healthcare professional.
Frequently Asked Questions
Severity. PMS causes uncomfortable but manageable symptoms. PMDD causes severe mood symptoms, such as depression, anxiety or anger, that disrupt work, relationships and daily life.
With daily symptom records over at least two cycles that show symptoms in the luteal phase and relief shortly after the period starts. A healthcare professional makes the diagnosis.
Usually not. People with PMDD tend to have normal hormone levels, but their brain reacts more strongly to the normal hormone changes after ovulation.