- Macular degeneration
- Macular holes
- Mammogram
- Mastitis
- Measles
- Medicines – tips to remember to take them
- Meibomian cyst
- Melanoma
- Meniere's disease
- Meningococcal disease
- Menopause
- Menorrhagia
- Men's health
- Menstruation
- Mental illness
- Mercury & health
- Mesothelioma
- Metabolic syndrome
- Migraine (severe headache)
- Miscarriage
- Molluscum contagiosum (viral skin infection)
- Morning sickness
- Motion sickness
- Motor neurone disease
- Mouth ulcers
- MRI Scan
- MRSA – methicillin-resistant Staphylococcus aureus
- Multiple sclerosis
- Mumps
- Muscular dystrophy
- Myalgic encephalopathy