SA
- Sarcoma; Cancer, bone (See: Bone Cancer)
SC
- Scarlatina (see: Scarlet fever)
SE
- Secondary brain cancer (See: Brain metastases)
- Seizure disorder (See: Epilepsy)
- Seizure, absence (See: Absence seizure)
- Septal defect, atrial (See: Atrial Septal Defect)
- Sexually transmitted diseases (STDs) (see: Sexually transmitted infections (STIs))
SI
- Sinus node dysfunction (See: Sick sinus syndrome)
- Sixth disease (See: Roseola)
SL
- Sleep apnea, obstructive (See: Obstructive sleep apnea)
- Slipped disk, Disc Herniation (See: Herniated disk)
SO
- Soft tissue, cancer (See: Soft tissue sarcoma)
- Solar keratosis (See: Actinic keratosis)
- Solar lentigines (See: Age spots)
- Sore throat (see: Pharyngitis)
SP
- Splenomegaly (See: Enlarged spleen)
- Sports-induced asthma (See: Exercise-induced asthma)
ST
- Stammering (See: Stuttering)
- Staph infection (See: Staphylococcus infection)
- Steele-Richardson-Olszewski syndrome (See: Progressive supranuclear palsy (PSP))
- Stenosing tenosynovitis (See: Trigger finger)
- Stenosis, pyloric (See: Pyloric stenosis)
- Stomach flu (See:Viral gastroenteritis)
- Stress cardiomyopathy (See: Broken heart syndrome)
SU
- Sun allergy (See: Polymorphous light eruption (PMLE))
- Sun poisoning (See: Polymorphous light eruption (PMLE))
- Sunstroke (see: Heatstroke)
SW
- Sweet's syndrome (See: Acute febrile neutrophilic dermatosis)
