A risk factor is something that increases your chance of getting a disease or condition.

It is possible to develop ]]>multiple sclerosis]]> (MS) with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing MS. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.

Risk factors for MS include:

Medical Conditions

A viral infection may trigger MS. Researchers have been investigating a type of herpes virus, human herpes virus-6, and Epstein-Barr virus. Some medical experts believe that it is the way certain people respond to the virus that may trigger MS.

People who have an isolated attack of ]]>optic neuritis]]> (inflammation of the optic nerve) have a high risk of developing MS.


Risk appears to be greatest between the ages of 16 and 40. This is when most people with MS are diagnosed.


At younger ages, women tend to be diagnosed with MS more frequently than men. However, the gender ratio is more equally balanced in people who develop MS later in life.

Genetic Factors

There may be a genetic component to MS, and sometimes it occurs in families. Researchers suspect more than one gene may be involved.

Ethnic Background

MS is more common in people of Northern European descent, especially people who are of Scandinavian background.

Other Factors

Other factors that may increase your risk of MS include:

  • ]]>Vitamin D]]>—People who have low vitamin D intake may also be at an increased risk.
  • Climate—Living in a colder climate may increase your risk of developing MS. This could be related to getting less sun exposure.
  • ]]>Smoking]]>—Smoking is also thought to be associated with a higher risk of MS.