It’s common to experience both physical and mental changes in the days leading up to a period.

In fact, 30 to 80 percent of people who menstruate are affected by premenstrual syndrome —more commonly known as PMS.

While headaches, stomach pains, and mood swings are some of the official PMS symptoms, they’re not the only premenstrual problems.

Body dysmorphia could be another.

Read on to find out more about this period-related condition.

“Period-related body dysmorphia may not be a recognized medical condition, but it is a real phenomenon,” says Cynthia Wesley, MD, a board certified OB-GYN in Charlotte, North Carolina.

“The distinguishing factor with body dysmorphia,” she adds, is that people “will temporarily see flaws in their body that are small or nonexistent.”

According to the people who experience it, these feelings only occur around the time of their period.

You may think period-related body dysmorphia fits the definition of premenstrual dysphoric disorder (PMDD). But the two conditions are different.

“PMDD is a severe form of PMS that negatively impacts a person’s ability to function,” explains Patricia Celan, MD, a psychiatry resident at Canada’s Dalhousie University.

Both PMS and PMDD can “cause bodily changes during the menstrual cycle,” adds Kecia Gaither, MD, who is double board certified in OB-GYN and maternal fetal medicine and practices in New York City.

Those changes can be anything from bloating and chest tenderness to fatigue.

The difference between PMDD and PMS, Gaither explains, is the dominance of specific emotional and behavioral symptoms.

She lists marked irritability, feelings of intense sadness, difficulty concentrating, and suicidal ideations as examples.

Period-related body dysmorphia, however, is “similar to body dysmorphic disorder (BDD), in which someone has difficulty with negative thoughts about their appearance that last for hours every day,” comments Celan.

“In some cases, symptoms only occur shortly before and in the first few days of a period,” adds Celan.

Well, there isn’t really any research into period-related body dysmorphia.

Some small-scale studies have found a link between periods and body dysmorphia.

A 2013 study of 44 females measured how participants perceived their body size during each phase of the menstrual cycle.

The “largest perceived body size and highest body dissatisfaction” occurred during menstruation.

Celan says the lack of research is because the condition is rare and because it may also be classed as “a subset of BDD.”

“Most people with period-related body dysmorphia could likely meet criteria even when not menstruating, though this isn’t the case for everyone,” adds Celan.

Without any research, the cause of period-related body dysmorphia is largely unknown.

There are theories, though. “It’s thought that these symptoms are due to monthly hormonal changes exacerbating an underlying psychological issue,” says Wesley.

Anxiety, bipolar disorder, and eating disorders are all mental health conditions known to be intensified by the menstrual cycle.

Again, there isn’t much research into whether body dysmorphic disorder could be influenced in the same way.

It’s also possible that certain emotions are amplified around the time of a period.

Several studies have found that emotional aspects may be regulated by two hormones involved in the menstrual cycle: estrogen and progesterone.

When levels of these hormones fluctuate, you may be more likely to feel down, potentially leading to symptoms of body dysmorphia.

Hormonal fluctuations are more severe during the luteal phase of the menstrual cycle. In other words, the days leading up to a period.

“Normal hormonal changes in a typical menstrual cycle affect everyone differently,” explains Celan.

“While some people respond to hormonal changes with irritability, others may become tearful, and others may become obsessive about physical appearance and perceived flaws.”

“The difference,” adds Celan, “can be explained by an underlying vulnerability to body dysmorphic disorder, due to perfectionism, past experiences, or genetics.”

People with body dysmorphia tend to have negative thoughts about their appearance.

Celan says spending hours thinking about the way you look, “researching options to change [your appearance], and excessive time spent hiding or ‘fixing’ perceived flaws” with skin picking and makeup “are an indication of a problem.”

This is especially true, she says, “if the time spent preoccupied with your appearance is taking time away from your responsibilities at work, school, or in your relationships.”

Period-related body dysmorphia tends to mean feeling this way right before, and potentially during, your period.

These feelings can eventually lead to stress and other conditions like depression.

Some people say they experience period-related body dysmorphia a few days before their period arrives.

Others experience it during their period.

Either way, it usually only lasts for a few days at the most.

Consider tracking your thoughts and feelings, whether through a physical diary or with a mobile app.

Seeing how your mood changes are tied to your menstrual cycle can help you realize these feelings aren’t permanent.

Boosting your self-care especially leading up to and during menstruation can also make a difference.

And increasing your exercise levels, decreasing red meat consumption, and watching how much you drink or smoke may help period-related disorders too, says Gaither.

Try also to avoid situations that cause high levels of stress. When you can’t avoid stressful circumstances, practice a mindfulness technique or two.

This can be anything from quick breathing exercises to full-blown meditation or aromatherapy.

If feelings of body dysmorphia are becoming too intense for you to cope alone, speak to a doctor.

Know that you don’t have to wait until things become severe. Doctors are there to help whenever you’re worried about a new, or lasting, symptom.

Cognitive behavioral therapy (CBT) is the first-line treatment for body dysmorphia, explains Celan, whether it’s period-related or not.

This kind of therapy “involves learning ways to challenge negative thoughts and perfectionism, coping with urges to skin pick or mirror check, and dealing with other negative habits as a result of the body dysmorphia.”

If your doctor believes hormonal fluctuations are to blame, they may recommend hormonal birth control.

If other treatments are unsuccessful, they may also consider prescribing medication such as an antidepressant.

However, Celan notes that “more research is needed to strongly support medication” when it comes to body dysmorphia.

Period-related body dysmorphia may be a medical mystery right now. But knowing that it can happen is important for any person who menstruates.

Know, too, that you don’t have to put up with negative feelings about the way you look whether they’re related to your period or present at other times.

There are ways to combat those feelings so they don’t interfere with your daily life. If you’re struggling to deal with them alone, doctors are always there to give a helping hand.

Lauren Sharkey is a U.K.-based journalist and author specializing in women’s issues. When she isn’t trying to discover a way to banish migraine, she can be found uncovering the answers to your lurking health questions. She has also written a book profiling young female activists across the globe and is currently building a community of such resisters. Catch her on Twitter.