Photo: Woman with MS in garden with orange flowers

Hormones and MS

Our MS community is full of inspirational women, from volunteers and campaigners to researchers, all working tirelessly to stop MS. But did you know women of reproductive age are almost three times more likely to be diagnosed with MS than men?

We still don’t fully understand exactly why these differences exist, but scientists think there could be several reasons. And one of these is hormones.


Hormones are a type of chemical messenger in the body. They travel through the bloodstream and instruct our bodies to do lots of important jobs – from regulating our temperature to telling us when we’re hungry.

Our sex hormones are a special type of hormone responsible for the development of the reproductive system and the physical differences between men and women. Oestrogen, testosterone and progesterone are all sex hormones.

Men and women have different levels of these sex hormones. Women have high levels of progesterone and oestrogen and low levels of testosterone, while men have high levels of testosterone and low levels of progesterone and oestrogen.

As well as giving men and women different physical features, we think these sex hormones play a role in MS.

Oestrogen and MS

Studies have shown symptoms of MS can get worse for some women after the menopause, when the body stops producing oestrogen. The menopause makes hormonal differences between men and women less extreme - which could also explain why men and women with late onset MS have a more similar experience of symptoms.

We also know that pregnant women generally have fewer symptoms. We think the high level of oestrogen seen in pregnancy has a protective effect. But when oestrogen levels decrease following birth, women have an increased risk of relapse.

Testosterone – a protective hormone?

A recent study shed some new light on the potential role of testosterone in MS. Scientists looked at a mouse model of MS called EAE (or experimental autoimmune encephalomyelitis). They showed that high levels of testosterone in male mice triggered an immune response that protected them from EAE.

In contrast, low levels of testosterone in female mice increased their risk of EAE. However, researchers concluded that this process alone wouldn’t be enough to protect against MS. And more research is needed to confirm if these results apply to people.

What does this mean for people with MS?

We hope understanding the role of hormones in MS could lead to new targets for treatments. However, more research is needed.

And hormones alone don’t explain the differences in MS between men and women. Researchers think genetic and environmental differences are also a key part of the puzzle.