Why do I feel like a different person the week before my period?

Premenstrual dysphoric disorder, or PMDD, is a severe reaction to the normal hormone changes in your menstrual cycle. In the week or two before a period, it can bring intense low mood, anxiety, irritability, anger, hopelessness and feeling out of control, along with physical symptoms. Symptoms usually ease within a few days of bleeding. It’s a recognised medical condition, and it’s treatable.

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Does this feel familiar?

You can predict your worst days by looking at your period tracker.
You said something cruel to your partner on Tuesday that you’d never normally say, and by Saturday you can’t believe it was you.
For ten days a month you’re convinced everyone hates you and your life is falling apart. Then your period starts and the fog lifts.
You’ve been told it’s ‘just PMS’ so many times that you’ve started to believe you’re overreacting.

What might be going on

With PMDD, your hormone levels are usually normal. What differs is how your brain responds to the rise and fall of oestrogen and progesterone after ovulation. That sensitivity can affect mood chemicals like serotonin, which is why the emotional symptoms can be so strong.

Symptoms appear in the luteal phase, the one to two weeks between ovulation and your period, and fade within a few days of bleeding. That cycle can make it hard to get diagnosed, because by the time you see a doctor you may feel fine.

Tracking your symptoms daily for at least two cycles is the most useful first step. Treatments from your GP can make a big difference, and therapy, women’s health support and lifestyle changes can help you cope with the hard weeks and protect your relationships and work.

One small thing. Just for today.

Start tracking today. Each day, rate your mood, anxiety, irritability and energy from 1 to 5 and note your cycle day. Two months of notes will make a GP appointment far more useful.

Let’s untangle a few assumptions

PMDD is just bad PMS.

It means your hormones are out of balance.

There’s nothing you can do except wait it out.

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A little perspective

The World Health Organization recognises PMDD in its International Classification of Diseases, and the International Association for Premenstrual Disorders estimates it affects around 1 in 20 women and people who menstruate.

Questions you might be asking

What is the difference between PMS and PMDD?

How is PMDD diagnosed?

What helps with PMDD?

Can PMDD get worse with age?

Can PMDD cause suicidal thoughts?

When to get medical help

Speak to your GP if your symptoms before your period affect your work, relationships or daily life. Bring your symptom diary if you can. PMDD can bring thoughts of self-harm or suicide in the days before a period. If that happens, it’s an emergency: call 999, NHS 111 and choose option 2, or Samaritans free on 116 123, any time. These feelings are a symptom, and help is available.

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