- macular degeneration
- mad cow disease
- major depression
- major depressive disorder
- malaria
- malignant brain tumors
- malignant hyperthermia
- malnutrition
- maple syrup urine disease
- maternal depression
- measles
- meckel syndrome
- melanoma
- meningitis
- meningococcal diseases
- mental disorder
- mental health
- mental health disorders
- mesothelioma
- metabolic syndrome
- metastases
- metastatic breast cancer
- metastatic melanoma
- methicillin resistant staphylococcus aureus
- migraine
- mild cognitive impairment
- mitochondrial dysfunction
- mood disorder
- mood disorders
- motor neuron disease
- motor neurone disease
- mouth cancer
- mrsa
- multi drug resistant gonorrhea
- multiple myeloma
- multiple personality disorder
- multiple sclerosis
- muscle degeneration
- muscle wasting disease
- muscular dystrophy
- myalgic encephalopathy
- myasthenia gravis
- myelodysplastic syndrome
- myocardial infarction