- Abdominal Pain
- Abortion, Habitual
- Abortion, Spontaneous
- Abscess
- Acute Chest Syndrome
- Acute Disease
- Acute Kidney Injury
- Acute Lung Injury
- Acute Otitis Media
- Acute Pain
- Airway Obstruction
- Akathisia, Drug-Induced
- Allergic Rhinitis
- Amputation
- Anaphylaxis
- Anemia
- Anemia, Iron-Deficiency
- Anemia, Sickle Cell
- Anovulation
- Anoxia
- Arthritis
- Arthritis, Rheumatoid
- Asthma
- Asthma, Exercise-Induced
- Athletic Injuries
- Attention Deficit Disorder with Hyperactivity