Find out about diagnosis and treatment of this cancer that has spread to the lymph nodes or other parts of the body.
Disease
Mitral valve stenosis
When the valve between the left heart chambers is narrowed, the heart doesn't get enough blood. Know the symptoms, causes and treatment of this type of heart valve disease.
Disease
Monoclonal gammopathy of undetermined significance (MGUS)
When bone marrow produces an unusual protein in the blood, it can sometimes lead to certain types of blood cancer.
Disease
Morning sickness
Learn more about nausea and vomiting during pregnancy. Learn about remedies that may help ease that queasy feeling.
Disease
Multiple sclerosis
This nervous system condition causes a range of symptoms. While there's no cure, it's possible to have long periods of remission.
Disease
Multiple system atrophy
This rare condition affects movement, blood pressure and other functions of the body.
Disease
Multisystem inflammatory syndrome in children (MIS-C) and COVID-19
Learn about symptoms of MIS-C, a serious condition linked to coronavirus disease 2019 (COVID-19). Get help fast if your child shows any signs.
Disease
Muscle strains
Minor strains may only overstretch a muscle or tendon, while more severe injuries may involve partial or complete tears in these tissues.