You begin having a symptom that you have not had before or you notice a significant change in symptoms that are already present.
Milder MS-type symptoms can be caused by many other conditions or may occur now and then in healthy people. For example, lots of people have minor numbness in their fingers or a mild dizzy spell once in a while. Stiffness and muscle weakness can result from being more active than usual. A wait-and-see approach (watchful waiting) is appropriate for these types of everyday aches and pains, so long as they do not continue.
If your symptoms occur more often or don't go away, talk to your doctor.
For people with MS
Talk to your doctor about what to expect from the disease and from treatment. MS is an unpredictable disease, but you probably can get some idea of what is "normal" and what symptoms or problems are reasons for concern.
Some people who have MS want active, regular support from their doctors. Others want to manage their condition on their own as much as possible. Wherever you are in this range, find out which signs or symptoms mean that you need to see your doctor. And seek help when you need it.