Harrison's Manual of Medicine
- obesity-hypoventilation syndrome (OHS)
- obinutuzumab, for CLL
- obturator neuropathy
- occipital cortex lesions
- occipital neuralgia
- ocrelizumab, for multiple sclerosis
- ocular gonorrhea
- ocular larva migrans
- ocular motor nerve palsy
- oculocephalic reflex
- oculopharyngeal dystrophy
- odynophagia
- ofatumumab, for CLL
- ofloxacin, for meningococcal prophylaxis
- OHS (obesity-hypoventilation syndrome)
- oligoanuria
- oligoblastic leukemia
- oligodendroglioma
- oligomenorrhea
- oliguria
- olopatadine, for allergic rhinitis
- omega-3 fatty acids, for dyslipidemia
- onchocercomata
- ondansetron, for nausea and vomiting
- onobotulinum toxin type A
- oophoritis, in mumps
- opening snap (heart sound)
- ophthalmia neonatorum
- ophthalmoscopic examination
- opicapone, for Parkinson's disease
- opisthorchiasis
- opsoclonus-myoclonus syndrome
- optic chiasm compression
- optic nerve (CN II), examination of
- optic neuropathy
- oral dissolution therapy, for gallstones
- oral-facial HSV infections
- oral leukoplakia
- oral poliovirus vaccine (OPV)
- oral rehydration solution (ORS), for cholera
- orchiectomy
- orchitis, in mumps
- orlistat, for obesity
- oromandibular dystonia
- Oroya fever
- oseltamivir, for influenza
- osmolar gap
- osmoregulation
- osmotic demyelination syndrome
- ostium primum
- ostium secundum
- ovarian ablation, for breast cancer
- ovarian cyst
- ovarian tumor
- overdiagnosis
- oxaliplatin, for colorectal cancer
- oxybutynin, for bladder hyperreflexia
- oxytocin