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)
A condition of blood plasma that produces altered antibodies that increase the risk of blood cancers and other conditions.
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.
This complicated condition may be triggered by an infection. While there's no cure for ME/CFS, treatment focuses on easing symptoms.
Disease
Myelodysplastic syndromes
Learn how medications and bone marrow transplants are used to control complications caused by these syndromes that affect the bone marrow.
Disease
Myofascial pain syndrome
In this condition, pressure on certain points in the muscles, called trigger points, can cause ongoing muscle pain.
Disease
NF2-related schwannomatosis (neurofibromatosis type 2)
NF2 is a rare condition that causes benign nerve tumors that can affect hearing, balance and other symptoms. Learn about symptoms, diagnosis and current treatments.