- OFEV
- Ocaliva
- Occlusal
- Ocufen
- Ocuflox
- Odefsey
- Olanzapine
- Olmesartan Medoxomil
- Olmesartan/HCTZ
- Olopatadine Eye Drop
- Omeprazole
- Omnaris
- Omnaris Nasal Spray
- Omnicef
- Omnipred
- Ondansetron
- Ondissolve
- One Touch Ultra Test Strips
- One Touch Verio Test Strips
- One-Alpha
- One-Alpha Drops
- Onglyza
- Online Medical Visit
- Opsumit
- Opticrom
- Optimune
- Optipranolol
- Optivar
- Oracea
- Orap
- Orapred
- Orgalutran Injection
- Orilissa
- 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
- Oseltamivir
- Osteofos
- Otezla
- Ovcon 35
- Ovestin Cream
- Ovol
- Oxistat Cream
- Oxistat Lotion
- Oxsoralen-Ultra
- Oxytrol
- Ozempic
- Ozurdex