Understanding Premenstrual Syndrome


Almost all women experience some premenstrual symptoms in the week or two before their period.

We don’t know the exact cause of PMS. But, what we do know is that the cyclic changes of the ovarian hormones estradiol and progesterone interact with some of the chemicals in your brain called neurotransmitters. The combination of these hormone and chemical changes are responsible for the physical and mood changes of PMS.

How Do These Hormone Changes Happen?

To help you understand what is going on, it is important to understand the dynamic changes that happen in your body between your periods. Although we tend to view the onset of bleeding as the “end of the month” it really is the beginning of a new cycle. Remember there are two major players in your pelvis, your uterus, and your ovaries. At the point that your period starts, your ovaries are already producing the hormones to prepare for the next ovulation. Technically this is known as the follicular phase of the menstrual cycle and lasts from the first day of your period until ovulation occurs, which happens roughly fourteen days later.

The hormonal changes triggered by ovulation are believed to be responsible for the symptoms you may experience during the second phase of your menstrual cycle. Technically, this second part of the menstrual cycle is called the luteal phase and lasts from ovulation until the first day of your period.

In common terms, this part of the menstrual cycle is called premenstrual and bothersome symptoms occurring during this time have come to be known as PMS or Premenstrual Syndrome. 

Making The Diagnosis

The diagnosis of Premenstrual Syndrome is based not only on the presence of symptoms but how much those symptoms bother you.

So, although most women have premenstrual symptoms only about 40 % of women are diagnosed with Premenstrual Syndrome/Premenstrual Dysphoria Disorder.

Studies show that women are most commonly diagnosed with PMS/PMDD after age 30. It is important to remember that the time of diagnosis isn’t the same as the onset of symptoms, and experts agree that PMS/PMDD can occur in any menstruating female regardless of her age.  The most important part of making the diagnosis is to be sure that the symptoms are not caused by another underlying medical condition.

The best way to determine that is for your doctor to take a complete medical history and for you to complete a symptom log for at least two cycles. 

Tracking Your Symptoms

This symptom log will help you and your doctor collect the data necessary to make the correct diagnosis of PMS or PMDD. Although the diagnosis can be made just based on history, it can be hard to remember exactly when during your cycle you had symptoms and that is key to making the correct diagnosis.

If possible track your symptoms before you see your healthcare provider. I would recommend using this symptom log or this period tracker app to help you collect the information.

You may have PMS if you have at least one of the following physical or mood-related symptoms, that you consider bothersome, that starts the week or two before your period and goes away during the first few days of bleeding. You may have PMDD, a very severe form of PMS, if your symptoms cause you significant social or physical impairment. For example, arguments at home or at work that affect your relationships or your job.

  • Irritability
  • Depression
  • Anger outbursts
  • Anxiety
  • Confusion
  • Social withdrawal
  • Crying spells
  • Poor concentration
  • Insomnia
  • Increased napping
  • Change in sexual desire
  • Breast tenderness
  • Abdominal bloating
  • Headache
  • Swelling of extremities
  • Fatigue
  • Weight gain
  • Muscle aches
  • Food cravings

Having these symptoms ONLY during the two weeks before your period is key. Some of the common medical conditions that have similar symptoms include:

Your symptom log will help to avoid a misdiagnosis.

Johnson S. Premenstrual Syndrome,Premenstrual Dysphoric Disorder, and Beyond. Obstetrics and Gynecology 2004;104: 845-859

American Congress of Obstetricians and Gynecologist Practice Bulletin Number 15. Premenstrual Syndrome. April 2000

Royal College of Obstetricians and Gynecologists Green-top Guideline Number 48. Management of Premenstrual Syndrome. December 2007

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