- Macular degeneration
- Magnesium test
- Magnetic resonance imaging scan
- Malaria
- Male breast cancer
- Male contraceptive pill
- Male thrush
- Malignant melanoma
- Malnutrition
- Marfan syndrome
- Mastectomy
- Mastitis
- ME
- Measles
- Medical records
- Medical research
- Medicines information
- Medium chain acyl dehydrogenase deficiency (MCADD)
- Ménière’s disease
- Meningitis
- Menopause
- Mental health
- Mental health services
- Mental health specialist services
- Metatarsalgia
- Methicillin-resistant staphylococcus aureus
- Microalbumin test
- Migraine
- Mini-stroke
- Miscarriage
- MMR
- Mobile phone safety
- Moles
- Molluscum contagiosum
- Mononucleosis
- Morning after pill
- Morning sickness
- Morton's neuroma
- Motion sickness
- Motor neurone disease
- Mountain sickness
- Mouth cancer
- Mouth ulcer
- MRI scan
- MRSA
- MS
- Mucositis
- Multiple myeloma
- Multiple sclerosis
- Mumps
- Munchausen syndrome by proxy
- Munchausen’s syndrome
- Muscular dystrophy
- Myalgic encephalomyelitis
- Myasthenia gravis
- Myocardial infarction
- Myopia