One day you feel great, and the next — well, you just don’t feel like yourself. You’re bloated and feeling all sorts of symptoms leading up to that time of the month.

You're not alone. These symptoms are part of what is known as premenstrual syndrome, or PMS. It's estimated that about 90% of females of reproductive age are affected. In a study that took place in Canada, 99% of women experienced symptoms before their period.

What is PMS?

Premenstrual syndrome (PMS) is a common condition that people with uteri typically experience in the days leading up to their period. It is thought to be the result of changes in the levels of sex hormones and serotonin at the beginning of menstruation, although its specific cause is unknown. PMS may entail both physical and emotional symptoms including, but not limited to cravings, bloating, dizziness, headaches, swelling in extremities, irritability, and fatigue. In some cases, these symptoms may be so intense that they interfere with the individual’s daily activities.

Symptoms can start anywhere from one to two weeks before your period begins. These symptoms usually disappear once your period starts. For some, certain symptoms of PMS, such as painful cramping, may last for the first few days of their period.


pink text that reads "more than 90% of women experience PMS symptoms"
yellow text that reads "PMS symptoms are most common for women in their 30's"
pink text that reads"3 out of 4 women are affected by period pain"

What are the Risk Factors for PMS?

Although the cause of PMS is not exactly clear, there may be several factors that can have an impact. Risk factors for PMS include:

  • Age

  • Stress

  • Higher body mass index (BMI)

  • Cigarette smoking

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1. Gao, M., et al. (2022). Global and regional prevalence and burden for premenstrual syndrome and premenstrual dysphoric disorder: A study protocol for systematic review and meta-analysis. Medicine. 101(1): e28528.

2. Dennerstein, L., et al. (2011). Global study of women's experiences of premenstrual symptoms and their effects on daily life. Menopause Int. 17(3): 88-95.

3. Armour, M., et al. (2019). The Prevalence and Academic Impact of Dysmenorrhea in 21,573 Young Women: A Systematic Review and Meta-Analysis. J Womens Health. 28(8): 1161-1171.

Additional references:

Bertone-Johnson, E. R., et al. (2008). Cigarette smoking and the development of premenstrual syndrome. Am J Epidemiol. 168(8): 938-945.

Deuster, P. A., et al. (1999). Biological, social, and behavioral factors associated with premenstrual syndrome. Arch Fam Med. 8(2): 122-128.

Jarosz, A. C., et al. (2017). Hormonal contraceptive use and prevalence of premenstrual symptoms in a multiethnic Canadian population. BMC Womens Health. 17(1): 87.

Masho, S. W., et al. (2005). Obesity as a risk factor for premenstrual syndrome. J Psychosom Obstet Gynaecol. 26(1): 33-39.