The severe soreness in the testicles after applying tincture of iodine is due to the fact that tincture of iodine contains irritants that cause burning pain in the skin of the testicles. Tincture of iodine is a topical disinfectant containing iodine, potassium iodide and ethanol, which has a strong killing effect on pathogenic microorganisms, and is commonly used for disinfecting healthy skin or for the treatment of certain skin diseases caused by microbial infections, in which potassium iodide can increase the solubility of iodine in ethanol. Iodine is highly irritating to the skin mucous membranes, and incorrect use of higher concentrations of iodine can also lead to skin damage, manifested as dermatitis or skin breakdown. If tincture of iodine is left for too long, acids can be produced and build up, making the irritant even more irritating and potentially further aggravating the skin damage caused by tincture of iodine after use. Because of its strong irritant properties, tincture of iodine should not be used on skin with wounds, nor should it be used to disinfect the eyes, mouth, perineum (where the testicles are located), and other mucous membranes. If testicular discomfort symptoms, need to go to a regular hospital as soon as possible, by the doctor according to the specific conditions, to formulate individualized diagnosis and treatment plan, so as not to delay the condition.