More than 750,000 people in North America live with ulcerative colitis (UC), an inflammatory bowel disease (IBD) that causes inflammation of the lining of the large intestine.

Most people with UC and other types of IBD are diagnosed between the ages of 15 and 35 — often the peak reproductive years. And while the condition is known for affecting the colon, it can also impact the reproductive system, including menstrual cycles.

Here’s what you should know about UC and menstruation.

People with UC sometimes experience changes to their menstrual cycle or irregular periods months before receiving an IBD diagnosis.

In a 2014 study among 121 women with IBD, 25 percent experienced a change in the timing of their menstrual cycle in the year leading up to their diagnosis. Roughly one-fifth of the participants also noticed changes in the duration of their flow.

However, the study also found that the participants’ menstrual cycles did become more regular and predictable in future years, perhaps due to treatment and control of IBD. The researchers believe that early stressors of UC and IBD may have been responsible for the irregular periods of people newly diagnosed with the condition, but more research is needed.

Despite the irregular menstruation that can occur before an IBD diagnosis, people with UC don’t have a greater chance of infertility, according to a 2013 systematic review of 11 studies.

Some medications used to manage UC can increase the risk of irregular menstruation. Corticosteroids in particular were linked with irregular periods in the 2014 study. Medications in this category include:

  • budesonide
  • prednisolone
  • methylprednisolone
  • prednisone

Other UC treatments, including thiopurine and anti-TNF agents, weren’t connected to irregular menstruation in that study.

In addition to potentially changing the duration and timing of menstrual cycles, some IBD medications may also make symptoms of menstruation worse during your period, as well as in the days leading up to it.

A 2020 study from Israel, which evaluated women between 18 and 50 years old who had UC or another type of IBD, found that participants who took biologics reported significantly higher levels of certain symptoms before menstruating, including:

  • irritability
  • nervousness
  • pelvic pain
  • fatigue

During menstruation, participants who took biologics for IBD were also more likely to report fatigue and pain in their pelvis, low back, and abdomen. Many of these, and other symptoms, were worse among people who smoked.

If you notice changes in your menstruation (or any other side effects) after taking certain UC medications, you may want to share your concerns with a doctor and see whether another treatment is available.

The same hormone-like compounds (prostaglandins) that cause uterine contractions and other painful period symptoms can also cause contractions in your colon, too. That, in turn, can make some UC symptoms more intense around your period.

Research from 2018, which studied more than 1,200 women with UC or Crohn’s disease (CD), showed that half of participants had worse IBD symptoms while menstruating.

A 2013 study of 47 people with IBD and 44 people in a control group found that those with IBD passed significantly more stools (including loose stools) and experienced more abdominal pain throughout their menstrual cycle than those without the condition.

That doesn’t necessarily mean you’ll experience a UC flare every time you get your period, but knowing about the potential for increased GI symptoms can help you plan ahead and find ways to cope throughout your menstrual cycle.

People who menstruate and live with UC may face an increased risk for anemia.

IBD, including UC, increases the risk of iron deficiency and anemia. According to research from 2018, as many as 45 percent of people with IBD have anemia.

UC can put you at risk for iron deficiency anemia for several reasons:

  • The long-term irritation and swelling in your intestines can interfere with your body’s ability to absorb iron as well as other nutrients.
  • You might not tolerate foods that are high in iron.
  • You might have low appetite.
  • Intestinal bleeding from ulcers causes blood loss.

The risk of anemia is even higher if you have a heavy period. Losing a lot of blood during your flow can use up more red blood cells than your body can produce, thus reducing your iron stores.

If you have UC and a heavy flow, you may want to look out for symptoms of anemia, including:

  • skin that looks paler than usual
  • shortness of breath
  • dizziness
  • fatigue or weakness
  • headaches
  • faster or slower heart rate
  • irregular heart rate
  • cold hands or feet

While mild anemia is usually easily treated, more severe cases can lead to serious health consequences and can sometimes be life threatening. Talk with a doctor if you experience symptoms of anemia or iron deficiency. They can check your iron levels and provide treatment recommendations, if necessary.

If UC or your medications seem to be having an affect on your menstrual cycle, contact a healthcare professional. They can help you get to the bottom of what’s going on and recommend ways to make your period more regular.

Here are some other signs you may want to connect with a doctor about your period and UC:

  • Your period hasn’t come for 90 days.
  • You suddenly experience irregular periods.
  • Your flow changes or becomes unusually heavy.
  • You have symptoms of anemia.
  • Your period comes more frequently than every 21 days.
  • Your period comes less frequently than every 35 days.
  • You experience extreme pain before or during your period.
  • You menstruate for more than a week.

Research has found connections between menstrual changes and UC. The disease and medication used to treat it have been linked with irregular periods, changes in flow, uncomfortable menstrual symptoms, and a higher risk of anemia.

Most of these changes occur in the months leading up to a UC diagnosis as well as early in the course of the disease. Irregular cycles tend to become more predictable over time.

You don’t have to live with painful, irregular periods, though. A doctor can help you figure out what’s affecting your menstrual cycle and offer potential solutions, such as a new medication or lifestyle change, that can ease symptoms.