Suddenly very itchy palms, consider and mosquito bites, sweat herpes, ringworm and other factors. 1. Mosquito bites: if in the hot summer, may be because of long-term in the mosquito more places, by mosquito bites palm, mosquitoes will be injected into the body of trace toxins, and then produce itching symptoms. 2. Sweat herpes: this is a blistering disease that occurs in the hands or feet, the patient may be in contact with allergens, emotional overstress and other factors, thus appearing on the palms of the hands of the sudden itchy phenomenon, there may also be tingling and burning sensation. 3. ringworm: this is mainly due to dermatophyte infection caused by ringworm, patients may be infected because of direct contact or use common items with the patient, thus appearing hand hyperkeratotic lesions, accompanied by flaking, dry, itchy symptoms. Suddenly very itchy palms may also be due to other reasons, so you need to cooperate with the doctor to do further examination and clarify the cause before treatment.