- Labor see Childbirth
- Laboratory Tests
- Lacerations see Wounds and Injuries
- Lactose Intolerance
- Language Problems see Speech and Communication Disorders; Speech and Language Problems in Children
- Large for Gestational Age see Birth Weight
- Laryngeal Cancer see Throat Cancer
- Laryngitis see Throat Disorders; Voice Disorders
- Laryngopharyngeal Cancer see Throat Cancer
- Laser Eye Surgery
- LASIK see Laser Eye Surgery
- Lassa Fever see Hemorrhagic Fevers
- Latex Allergy
- Latino and Hispanic American Health
- Lazy Eye see Amblyopia
- LDL: The "Bad" Cholesterol
- lead exposure see Lead Poisoning
- Lead Poisoning
- Learning Disabilities
- Leg Cramps see Leg Injuries and Disorders; Muscle Cramps
- Leg Injuries and Disorders
- Legg-Calve-Perthes Disease see Osteonecrosis
- Legionnaires' Disease
- Leishmaniasis
- Leprosy see Mycobacterial Infections
- Lesbian Health see LGBTQIA+ Health
- Leukemia
- Leukemia, Acute Lymphoblastic see Acute Lymphocytic Leukemia
- Leukemia, Acute Lymphocytic see Acute Lymphocytic Leukemia
- Leukemia, Childhood see Childhood Leukemia
- Leukemia, Chronic Lymphocytic see Chronic Lymphocytic Leukemia
- Leukemia, Myeloblastic, Acute see Acute Myeloid Leukemia
- Leukemia, Myelogenous, Acute see Acute Myeloid Leukemia
- Leukemia, Myeloid, Acute see Acute Myeloid Leukemia
- Leukemia, Myeloid, Chronic see Chronic Myeloid Leukemia
- Leukodystrophies
- Lewy Body Dementia
- LGBTQIA+ Health
- Life Support see Critical Care
- Ligament Injuries see Sprains and Strains
- Lightning Strikes see Electrical Injuries
- Limb Loss
- Lipid Metabolism Disorders
- Listeria Infections
- Liver Cancer
- Liver Cirrhosis see Cirrhosis
- Liver Diseases
- Liver Spots see Skin Aging
- Liver Transplantation
- Living Wills see Advance Directives
- Living with Cancer see Cancer--Living with Cancer
- Living with HIV
- Lockjaw see Tetanus
- Long COVID see Post-COVID Conditions (Long COVID)
- Long-Term Care see Assisted Living; Nursing Homes
- Lou Gehrig's Disease see Amyotrophic Lateral Sclerosis
- Low Back Pain see Back Pain
- Low Birth Weight see Birth Weight
- Low Blood Pressure
- Low Blood Sugar see Hypoglycemia
- Low Cholesterol Diet see How to Lower Cholesterol with Diet
- Low Sperm Count see Male Infertility
- Low Vision see Vision Impairment and Blindness
- LTK see Laser Eye Surgery
- Lumbago see Back Pain
- Lumpectomy see Mastectomy
- Lung Cancer
- Lung Diseases
- Lung Rehabilitation see Pulmonary Rehabilitation
- Lung Transplantation
- Lupus
- Lyme Disease
- Lymph Nodes see Lymphatic Diseases
- Lymphatic Diseases
- Lymphatic Obstruction see Lymphedema
- Lymphedema
- Lymphoma