The rate of reinfection of onychomycosis is higher than that of onychomycosis, and there are several factors that can cause reinfection: 1. Drug resistance of the causative fungus: The incidence of fungal infections has increased dramatically in recent years. 2. Reinfection: Curing nail fungus without also curing tinea pedis leads to reinfection of the nails, which is an important factor in the recurrence of nail fungus. 3. Insufficient treatment: In some patients, the medication is stopped when the finger (toe) nail is about to return to its normal form, i.e., it is considered completely cured, and the treatment is not completed, which can also produce reinfection. In a clinical study, only 52% of patients completed oral medication under the guidance of a physician, and 25% of patients thought they were cured and stopped medication on their own. The poor compliance of patients is also related to the long treatment course of nail fungus, high cost and lack of understanding of its harmful effects. 4, nail malnutrition: due to other diseases and other reasons, causing nail malnutrition, so that the ability of the nail plate own defense fungus decreased and the nail growth rate is slow, and the finger (toe) nail re-infection. 5, basic diseases: diabetes, low immunity, the elderly and other people are nail fungal disease groups, easy to re-infection. 6, trauma: again trauma caused by pathogenic fungi invade the nail plate re-infection, this case is also quite a lot. 7, chemical stimulation: long-term exposure to gasoline, paint, detergents and strong alkaline soap and other substances, changing the normal skin nail surface pH and defense ability, and lead to reinfection. 8. Poor drug absorption: In some special cases, such as the appearance of diseased nail cavities can cause overgrowth of dermatophytes in the nail or lead to sponge-like degeneration of the nail bed keratin, thus making the cavity contain clumps of necrotic keratin and a large number of mycelium, and the drug cannot diffuse into these clumps of mycelium, leading to treatment failure. In this case, surgical nail extraction or 40% urea sealed nail removal combined with oral drug therapy is more effective. 9, drug interactions: comparatively speaking, drug interactions have relatively little effect on the efficacy of nail fungus disease. Mainly in the liver drug enzyme inducers (such as rifampin, etc.) can accelerate the plasma clearance of terbinol, so that the blood drug concentration decreased, liver drug enzyme inhibitors can inhibit the plasma clearance of terbinol, so that the blood drug concentration increased. Therefore, when these drugs are used in combination, the dose of the drug should be adjusted appropriately so that it is within the range of effective blood concentration.