- Opalescence PF
- Opalescence Whitening
- Opana
- Opana ER
- Opcon-A
- Opdivo
- Ophthaine
- Ophthetic
- Ophthocort
- Opipramol
- Opium
- Opium Alkaloids With Morphine
- Opium Derivatives And Expectorants
- Opium Derivatives And Mucolytics
- Oprelvekin
- Opsumit
- Optase
- Opticaine
- Opticrom
- Opticyl
- OptiFlex-C
- Optiflex-G
- Optigene
- Optima Plus
- Optimine
- Optimmune
- Optimum brand of activated charcoal
- Optimum brand of magnesium gluconate
- OptiPranolol
- Optivar