- Gallbladder and bile duct cancer
- Gallbladder cancer
- Ganglion cyst
- Gangrene (death of body tissue)
- Gastric ulcer (stomach ulcer)
- Gastritis (stomach inflammation)
- Gastroenteritis (intestinal infection)
- Gastroesophageal reflux (GERD, heartburn)
- Gastrointestinal bleeding (stomach, intestine bleeding)
- Gastrointestinal perforation (hole in the stomach, intestine)
- Gastroparesis (stomach muscle malfunction)
- Generalized seizure disorder (generalized epilepsy)
- Genital herpes (HSV type 2 infection)
- Genital warts (HPV, Human papillomavirus infection)
- Gestational diabetes (diabetes during pregnancy)
- Gestational hypertension (high blood pressure in pregnancy)
- Giardiasis (giardia infection)
- Gilbert's disease (liver abnormality)
- Gingivitis (inflammation of the gums)
- Glaucoma (elevated eye pressure)
- Glomerulonephritis (kidney disease)
- Glossitis
- Glossodynia
- Goiter (enlarged thyroid)
- Golfer's elbow (medial epicondylitis of elbow)
- Goodpasture syndrome (disease of kidneys and lungs)
- Gout (uric acid crystals in the joint causing inflammation)
- Graves' disease (overproduction of thyroid hormone)
- Graves’ eye disease (Graves’ ophthalmopathy)
- Greater trochanteric bursitis (hip bursitis)
- Guillain Barre syndrome (ascending muscle weakness)