Between 3 and 8% of women have PMDD, a severe form of PMS with depression-like symptoms.

"For the three days leading up to my period, I was suicidal, anxious and irritable. I'd have fits of rage; I felt unglued. Then, I'd get my period and I'd be fine," says Jennifer, who asked us not to use her last name. Her psychotherapist suggested PMDD two years ago as a possible cause for her mood swings.

PMDD is like PMS's bigger, badder sister. It's another way of saying very severe PMS, says Dr. Samantha Saffy, a psychiatrist in Vancouver. In order to get a PMDD diagnosis, you need to experience the disorder's depression-like symptoms—mood swings, irritability, anger, feelings of hopelessness, anxiety, fatigue, difficulty concentrating, insomnia and a decreased interest in usual activities—more months than not. They should occur in the week leading up to menses, then improve after your period starts. 

It can be difficult to get a diagnosis. Jennifer had been to three physicians with no luck. But just knowing PMDD exists might be helpful. "Often, being aware of your condition through education can help ease symptoms," says Dr. Tanya Tulipan, a psychiatrist specializing in reproductive mental health in Halifax. "If you know that certain days of the month will be more challenging for you, you can plan around them to minimize stress. Healthy habits such as getting adequate sleep, exercising regularly and eating healthily are known to ease symptoms, too." Cognitive behavioural therapy and mindfulness can also help, but "if none of these strategies works, your family doctor can suggest an antidepressant that you can take continuously or even just for the week that you have your symptoms," says Dr. Tulipan. 

Read more:
Here's what you need to know to combat common period problems
4  ways to have a lighter period