- Labour
- Labyrinthitis
- Lacerations
- Lactose intolerance
- Laparoscopic cholecystectomy
- Laparoscopy
- Laryngeal (larynx) cancer
- Laryngitis
- Laryngotracheitis
- Lateral epicondylitis
- Laxatives
- Lazy eye
- LDH
- Leg cramps
- Leg ulcer, venous
- Legionnaire's disease
- Leptospirosis
- Leukaemia, acute
- Leukaemia, chronic
- Leukoplakia
- Lice (head)
- Lice (pubic)
- Lichen planus
- Lipid-lowering medicines
- Liposuction
- Listeriosis
- Liver cancer
- Liver disease (alcoholic)
- Liver transplant
- Local anaesthetic
- Local Involvement Network (LINk)
- Lockjaw
- Long-sightedness
- Low blood pressure
- Low dose aspirin
- Lumbar decompressive surgery
- Lumbar puncture
- Lumpy jaw
- Lung cancer
- Lung transplant
- Lupus
- Lyme disease
- Lymphoedema
- Lymphoma