| Radiation Therapy | |
| Radiculitis | Disorders of the roots of the nerves. |
| Radioisotope | |
| Radiotherapy | See Radiation Therapy. |
| Ranunculus | |
| Raw Glandulars | See Glandular. |
| Raynaud's | See Raynaud's Phenomenon. |
| Raynauds Disease | See Raynaud's Phenomenon. |
| Raynaud's Disease | See Raynaud's Phenomenon. |
| Raynauds Phenomenon | See Raynaud's Phenomenon. |
| Raynaud's Phenomenon | |
| Raynauds Syndrome | See Raynaud's Phenomenon. |
| Raynaud's Syndrome | See Raynaud's Phenomenon. |
| RBC | See Red Blood Cell. |
| rBGH | See Recombinant Bovine Growth Hormone. |
| RDA | Recommended Daily Allowance of vitamins or other nutrients as determined by the FDA. U.S. RDAs are more widely used than RDAs, and focus on 3 age groups: Infants of 0-12 months; Children of 1-4 years; Adults and children of more than 4 years. |
| RDAs | See RDA. |
| Recombinant Bovine Growth Hormone | |
| Red Blood Cell | |
| Red Blood Cells | See Red Blood Cell. |
| Refined Sugar | |
| Refined Sugars | See Refined Sugar. |
| Reflux Nephropathy | |
| Renal | See Kidneys. |
| Renal Insufficiency | See Chronic Renal Failure. |
| Restless Legs Syndrome | |
| Retina | |
| Retinal | See Retina. |
| Retinal Edema | Accumulation of fluid in the retina. |
| Retinopathy | |
| Retrovirus | |
| Rhabdomyoma | See Rhabdomyomas. |
| Rhabdomyomas | |
| Rhabdomyosarcoma | See Rhabdomyosarcomas. |
| Rhabdomyosarcomas | |
| Rhagades | Chaps, cracks, or fissures. |
| Rheological | Deformative flow of materials, usually blood. |
| Rheumatism | |
| Rheumatoid | See Rheumatism. |
| Rheumatoid Arthritis | |
| Rheumatoid Iritis | See Iritis. |
| Rheumatologist | A doctor who has received special training in the diagnosis and treatment of problems with joints, muscles and bones. |
| Rheumatologists | See Rheumatologist. |
| Rhinitis | |
| Rhinophyma | |
| Riboflavin | |
| Rickets | |
| Ringworm | See Tineas. |
| RNA | A ribonucleic acid found in plant and animal cells; a complex protein chemical. Important in the coding of genetic information with DNA carrying information from the nucleus of the cell into the cytoplasm. |
| Roborant | Strengthening agent, tonic. |
| Roemheld's | Roemheld's syndrome: Gastro-cardiac syndrome. |
| ROS | Reactive Oxygen Species. Molecules including free radicals and other oxygen species. |
| Rutin | |
