- OFEV
- Ocaliva
- Occlusal
- Ocufen
- Ocuflox
- Odefsey
- Ofev
- Olumiant
- Omnaris
- Omnaris Nasal Spray
- Omnipred
- Ondansetron
- Ondissolve
- One Touch Delica Lancets
- One Touch Verio Test Strips
- Ongentys
- Onglyza
- Opsumit
- Opticrom
- Optimmune Ointment
- Optimune
- Optipranolol
- Optivar
- Oracea
- Oralair
- Orap
- Orapred
- Orgalutran Injection
- Orilissa
- Orinase
- Orlistat
- Ortho 0.5/35 Discreet 21
- Ortho Cyclen
- Ortho Evra
- Ortho Micronor
- Ortho Novum 7/7/7
- Ortho Tri-Cyclen
- Ortho Tri-Cyclen Lo
- Ortho-Cept
- Orthovisc
- Orudis
- Orudis E
- Oruvail
- Osphena
- Ospolot
- Osteofos
- Otezla
- Otomax
- Otrivin Nasal Spray Adult
- Ovcon 35
- Ovestin Cream
- Ovol
- Oxistat Cream
- Oxistat Lotion
- Oxsoralen-Ultra
- Oxytrol
- Ozempic
- Ozonol Ointment
- Ozurdex