Why do flat warts suddenly become itchy?

Itching of flat warts may be caused by multiple factors. Flat warts are caused by human papillomavirus (HPV) infection; when the virus proliferates excessively or becomes active, it may stimulate peripheral nerves, leading to itching. Excessive mental stress and significant emotional fluctuations may also cause autonomic nervous system dysfunction, resulting in reactive itching at the wart site. Contact with allergens, such as animal fur, pollen, etc., may trigger allergic skin reactions, causing itching at the flat wart site. Additionally, during improvement or treatment of flat warts, mild itching may occur due to medication irritation or enhanced immune function. Insect bites or coexisting skin conditions at the flat wart site, such as eczema or herpes, may also cause itching.