- Iron deficiency anemia
- Interstitial lung disease
- Insufficient blood supply to the cerebral arteries
- Injury, Poisoning, and First Aid
- Inhalation injury
- Influenza A
- Human infection with highly pathogenic avian influenza
- High fever
- Heavy chain disease
- Gasoline poisoning
- Formaldehyde poisoning
- Drug-induced obesity
- Disulfiram-like reaction
- Disseminated intravascular coagulation
- Difficulty breathing
- Dehydration