- Scars
- Schizophrenia
- Scoliosis
- Seasonal affective disorder
- Self-injury
- Septic shock
- Short-sightedness
- Sickle-cell anaemia
- Sinusitis
- Sjogren's syndrome
- Slapped cheek syndrome
- Sleep apnoea
- Slipped disc
- Snoring
- Spina bifida
- Spinal muscular atrophy
- Sports injuries
- Staphylococcal infections
- Stillbirth
- Streptococcal infections
- Stress
- Subarachnoid haemorrhage
- Subdural haematoma
- Suicide
- Supraventricular tachycardia
- Stomach cancer
- Skin cancer (malignant melanoma)
- Scurvy
- Smelly feet (bromodosis)
- Sweating, excessive (hyperhidrosis)
- Sex change
- Scabies
- Sciatica
- Sick building syndrome
- Sexual health clinics
- Sexually transmitted infections
- Stretch marks
- Syphilis
- Sore throat
- Sunburn
- Sudden infant death syndrome (SIDS)
- Schistosomiasis
- SARS
- Scarlet fever
- Shingles
- Squint
- SSRIs (selective serotonin reuptake inhibitors)
- Small bowel transplant
- Smear test
- Stroke
- Smoking (quitting)
- Sarcoma (bone cancer)
- Seasonal allergic rhinitis
- Selective serotonin reuptake inhibitors
- Singultus
- Stem cell transplant
- Stoma
- Stomach ulcer
- Stria
- Swimmer's ear
- Systemic lupus erythematosus
- Sickness and diarrhoea in children
- Solvent abuse
- Sprains and strains
- Shoulder pain
- Statins
- Stings, insect
- Stings, marine creatures
- Snake bites
- Skin cancer (non-melanoma)
- Swine flu
- Scleroderma
- Stress incontinence