The reason why oxytetracycline tablets cannot treat gray nails is because gray nails are fungal infections. oxytetracycline tablets are tetracycline antibiotics, which mainly target bacterial infections, although there are some serious gray nail ulcers that can be followed by bacterial infections, but the root cause of the disease is still fungal. In addition, after the oral consumption of hygromycin tablets for intestinal damage, liver damage and kidney damage are very large, but also easy to appear tetracycline teeth, therefore, this drug is rarely used in clinical practice. You should go to the dermatology department of a regular hospital and be prescribed the appropriate medication for the appearance of gray nails. Don’t buy drugs at random, because the side effects of drugs for fungal infections are also very high and need to be taken orally under the guidance of a doctor. Due to the stubborn nature of gray nails, most topical medications are not particularly effective.