Primary progressive multiple sclerosis (MS) is a form of MS in which the disease is progressive from the start. Symptoms such as muscle weakness, leg dragging, and stiffness become worse, and nerve function deteriorates steadily, though this occurs at different rates in different people.

Primary progressive MS occurs in just a small number of people with MS. In these people, the illness may be severe from the start with a quick progression of neurological problems over several months. There are no periods when symptoms do not occur (remission).

While there is no cure for MS, medications can reduce the number, frequency, and severity of relapses and may slow the progression of the disease.