Itching is a common occurrence. Mild itching is harmless however, excessive itching is a symptom of underlying medical condition. The causes of itching are - Food allergy e.g. Gluten, peanuts - Pollen - Insect bites e.g. bugs, bed bugs, fleas, mosquitoes - Medicines e.g. opioids, anti-fungals - Dermatological conditions e.g. Pruritis, eczema, dry skin - Cosmetics - Chemicals and poisons - Plants e.g. Poison Ivy, Poison Oal - Parasites e.g. Lice, scabies, pinworms - Diseases that affect nervous system e.g. Shingles, Diabetes - Neurological conditions e.g. Multiple sclerosis, Herpes Zoster - Internal disorders e.g. Cirrhosis, kidney failure, thyroid diseases - Psychiatric disorders e.g. Obsessive Compulsive Disorder, anxiety - Pregnancy