There are different clinical manifestations of multiple sclerosis. During an attack, a patient experiences a sudden deterioration in normal physical abilities that may range from mild to severe. This attack, sometimes referred to as an exacerbation of multiple sclerosis, typically lasts more than 24 hours and generally more than a few weeks (rarely more than four weeks).

About 65-80% of patients begin with Relapsing-Remitting (RR) MS, the most common type. This is characterised by relapses (also known as exacerbations) during which time new symptoms can appear and old ones resurface or worsen. The relapses are followed by periods of remission, during which time the person fully or partially recovers from the deficits acquired during the relapse. Relapses can last for days, weeks or months and recovery can be slow and gradual or almost instantaneous. It may be weeks to decades between relapses.

In Primary-Progressive (PP) MS there is a continuous, gradual decline in a patient's physical abilities from the outset rather than relapses. There may be periods of a leveling off of disease activity and, as with secondary progressive, there may be good and bad days or weeks. PPmultiple sclerosis differs from Relapsing/Remitting and Secondary Progressive in that onset is typically in the late thirties or early forties, men are as likely women to develop it and initial disease activity is in the spinal cord and not in the brain. Primary Progressive multiple sclerosis often migrates into the brain, but is less likely to damage brain areas than relapsing/remitting or secondary progressive - for example, people with Primary Progressive are less likely to develop cognitive problems.About 10%-20% of patients begin with PP-MS.

Patients beginning with RR-MS can then enter a phase where relapses are rare but more disability accumulates, and are said to have the Secondary-Progressive (SP) type of multiple sclerosis. In the early phases of Secondary Progressive, the person may still experience a few relapses but after a while these merge into a general progression. People with secondary progressive may experience good and bad days or weeks, but, apart from some remission following relapsing episodes, no real recovery. About 50% of RR-MS patients will develop SP-MS within 10 years

Progressive-Relapsing (PR) MS is a type of multiple sclerosis characterized by a steady decline in abilities accompanied by sporadic attacks. There may be periods of a leveling off of disease activity and, as with secondary progressive, there may be good and bad days or weeks. PPmultiple sclerosis differs from Relapsing/Remitting and Secondary Progressive in that onset is typically in the late thirties or early forties, men are as likely women to develop it and initial disease activity is in the spinal cord and not in the brain. Primary Progressive multiple sclerosis often migrates into the brain, but is less likely to damage brain areas than relapsing/remitting or secondary progressive - for example, people with Primary Progressive are less likely to develop cognitive problems.

There are also cases of of multiple sclerosis that are mild and can be recognized only retrospectively after many years and also rare cases of extremely rapid progression of multiple sclerosis symptoms (sometimes fatal) known as malignant or fulminant (Marburg variant) multiple sclerosis.