Multiple sclerosis (MS) affects women 3 times as often as men. Since hormones play a big role in the disease, it’s not surprising that MS can affect menstrual periods — which are also hormone-driven.

Some women notice a change in period symptoms once they’re diagnosed with MS. They may see an increase in premenstrual syndrome (PMS) symptoms like mood shifts, irritability, fatigue, pain, poor concentration, and a loss of interest in sex.

This collection of symptoms typically appears a few days before your period and disappears a few days after you get it.

Sometimes it can be hard to tell the difference between MS and PMS symptoms. After all, fatigue, mood shifts, and sexual problems are common with both conditions.

Read on to learn more about how MS can cause changes in your menstrual cycle.

If you feel like your periods changed after your MS diagnosis, you could be right.

In one study comparing women with MS to those without it, researchers found that those with the condition experienced more irregular periods and symptoms of PMS.

One reason for the change is that your body temperature rises slightly during your period. Even a tiny increase in temperature can make MS symptoms worse.

Hormones are the other likely cause of the relationship between MS and your menstrual cycle. Sex hormones — estrogen and progesterone — both regulate your menstrual cycle and affect MS activity.

Right before you get your period, levels of these hormones plummet, setting off symptoms.

Hormones are also the reason why MS symptoms change during pregnancy. Rising estrogen and progesterone during those 9 months can reduce MS symptoms for some (until after they deliver).

Some of the medications that manage MS can also affect the menstrual cycle.

Beta interferon, a treatment for relapsing forms of the condition, can cause irregular bleeding. It can also make your periods come earlier or later than usual.

The relationship between MS and your menstrual cycle goes both ways. Research finds you’re more likely to have a relapse of motor symptoms, vision problems, and trouble with coordination in the 3 days before your period.

Doctors call these temporary bouts of symptoms pseudoexacerbations. Sometimes it’s hard to know whether symptoms like weakness, pain, and fatigue are from MS or your period because they can feel very similar.

Your mental sharpness and motor skills can also experience changes right around the time your period is due. In a 2019 study, people with MS did worse on tests of mental and physical performance just before their period.

One way to prevent bothersome PMS symptoms is to take birth control pills or use other hormonal contraceptives. The hormones in these treatments will help regulate your menstrual cycle, and should make your periods lighter and easier overall.

Medications that manage MS may also help with at least some aspects of difficult periods. Drugs that help to regulate the immune system can improve the mental fog some women experience right before their periods.

You can also try a nonsteroidal anti-inflammatory drug (NSAID) like aspirin or ibuprofen (Advil, Motrin). These over-the-counter pain relievers can ease PMS discomforts like cramps and sore breasts.

Some women dread the days before their period starts because of PMS symptoms. MS can make periods more unpredictable and more uncomfortable. Periods can sometimes worsen MS symptoms too.

If you’re experiencing very painful and unpleasant periods, see your OB-GYN and neurologist for guidance.

The OB-GYN may be able to prescribe birth control pills or other hormonal contraceptives to lighten your symptoms, while your neurologist can prescribe medications that help with MS symptoms.