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 real change in their periods once they’re diagnosed. 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 your MS and PMS symptoms. After all, fatigue, mood shifts, and sexual problems are common with both conditions.

Not sure whether your autoimmune disease is affecting your periods, or vice versa? Here’s a guide to help you figure out your menstrual cycle with MS.

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 your 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 give some women a reprieve from their MS symptoms until after they deliver.

Some of the medications you take to manage your MS can also affect your menstrual cycle. Beta interferon, a treatment for relapsing forms of the disease, 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 three 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 look very similar.

Your mental sharpness and motor skills can also take a hit 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 go on the birth control pill. The hormones in the pill will help regulate your menstrual cycle, and should make your periods lighter and easier overall.

Medications you take to manage your MS may also help with at least some aspects of difficult periods. Drugs that help to regulate your 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 like mood shifts, pain, and fatigue. 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 put you on birth control pills to lighten your symptoms, while your neurologist can prescribe medications that help with MS symptoms.