Premenstrual dysphoric disorder: The extreme PMS that affects less than 8pc of women
Like lots of women, I am like a briar in the days before my period comes.
Of course, it's not (entirely) my fault.
Fluctuating levels of hormones like oestrogen mean that many gals can feel anxious, irritable or teary before their monthly visitor arrives.
Still, for some of us these emotional ups and downs can be even more extreme due to two conditions that aren't often spoken about.
Premenstrual dysphoric disorder (PMDD)
Premenstrual dysphoric disorder is a condition that causes severe and debilitating emotional symptoms during PMS.
These can include extreme mood swings; anger and conflict with others; depression and feelings of hopelessness; loss of interest in usual activities and trouble concentrating.
There can also be physical symptoms like sleeplessness; a;adaches; joint and muscle pain; acute cramping and bloating; sore breasts and hot flashes.
While some of these symptoms do overlap with PMS, premenstrual dysphoric disorder is far more rare.
Three quarters of menstruating women get PMS but this condition only affects between three to eight per cent of us.
Knowledge about PMDD is pretty new. Only in 2013 was it recognised as a depressive disorder by the American Psychiatric Association in its Manual of Mental Disorders.
PMDD can have a seriously disruptive impact on sufferers' lives; affecting their work, studies, social life and relationships.
If you think you could have it, you should speak with your doctor about potential solutions.
Premenstrual exacerbation (PME)
Premenstrual exacerbation occurs when your period makes an existing psychiatric condition even worse.
Conditions that fall under this include major depressive disorder, persistent depressive disorder, anxiety, suicidal feelings, eating disorders, schizophrenia and alcoholism.
It's estimated that half of all of women who seek help for PMS also suffer with an existing mental health issue.
This means that PME is likely to be a lot more common than many of us know.
Similarly to PMDD, it's recommended that you consult your doctor if you feel like you suffer with PME.
For the month of February, Her will be #OnTheRag.
We'll be chatting all things periods, products and pain as we delve deep inside the uterus to figure out why we bleed and - more importantly - how we cope.
We'll also be talking to the experts about some of the period related conditions you have heard of - and all of the ones that you haven't.
Want to get in touch? Email us at firstname.lastname@example.org.