Clinical side effects of macrolides in addition to the common gastrointestinal reactions, recently it has been found that the incidence of local reactions after injection is relatively high, such as pain and itching and local inflammation. Severe skin reactions include erythema multiforme, acute systemic eruption impetigo, Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reactions with eosinophilia and systemic symptoms. The clinical study is a single-center, randomized, open, single-dose trial design. The clinical study plans to enroll 30 subjects to evaluate the incidence and severity of pain and pruritus after a single skin test in healthy subjects. A total of 30 subjects were randomly divided into 2 groups with 15 cases in each group. Erythromycin or azithromycin skin test will be performed on the left hand, and the same amount of normal saline will be injected into the right hand as the control. This clinical observation experiment helps improve the side effects and promotes upgrading macrolide antibiotics during clinical application.

Inclusion Criteria:

• The age range of the subjects is from 18 to 65 years old, and there is no gender restriction for the subjects;
• Male subjects weigh more than 50kg (including 50kg) and female subjects weigh more than 45kg (including 45kg); Body mass index [BMI= weight (kg)/ height (m) 2] is in the range of 19-26 kg/m 2, including the critical value;
• The physical examination, laboratory examination, 12 lead electrocardiogram, chest X-ray (anterior lateral and lateral), and vital sign examination of the subjects are all within normal range or abnormal;
• The subjects' blood routine, blood biochemistry, and urine routine are within the normal range;

Exclusion Criteria:

• People have a clinical history of the following diseases (including but not limited to gastrointestinal, cardiovascular, musculoskeletal, endocrine, hematological, psychiatric, renal, liver, bronchial, neurological, immune, lipid metabolism disorders, or known or suspected malignant tumors);
• Patients who experience abnormal bleeding within the first 6 months of screening do not meet the criteria;
• Pregnant and lactating women; Or female urine pregnancy test positive;
• Blood routine, blood biochemistry, and urine routine examination are significantly abnormal;
• Have a history of hospitalization or surgery within 6 months before screening;
• Participate in other drug clinical studies within 3 months before screening;
• Patients with a history of prescription drug abuse and illicit drug abuse or positive urine drug screening within 6 months before screening;
• A history of alcohol abuse in the 6 months before screening, that is, drinking more than 14 units of alcohol per week (1 single drink =360 mL beer or 45 mL spirits with 40% alcohol or 150 mL wine);
• During the six months before screening, individuals who smoke more than 10 cigarettes per day or test positive for nicotine in their urine;
• Within the 3 months before screening, individuals consumed more than 1 liter of strong tea, coffee, and/or caffeinated beverages per day;
• Within 3 months before screening, the patient has a history of blood donation or acute blood loss (≥ 400mL)；
• Within 2 weeks before the screening, people use prescription drugs, over-the-counter drugs, traditional Chinese patent medicines, and simple preparations or Chinese herbal medicines;
• People have a history of allergy to any of the components of the test drug (erythromycin, azithromycin, other macrolides or ketolides);
• Any other factors deemed unsuitable for participation in this study by the investigator.

The study is conducted in healthy adults aged 18-65 years， and there is no gender restriction for the subjects.