The main ingredient of Erythromycin Granules is Erythromycin, which is also an oral erythromycin preparation that is absorbed orally and converted into erythromycin for action in the body. Erythromycin belongs to macrolide antibiotics, which is a kind of antibacterial agent, inhibiting the growth and reproduction of bacteria by inhibiting the synthesis of bacterial proteins, and can kill certain bacteria at high concentration. In addition, it also has an inhibitory effect on other pathogens such as Mycoplasma pneumoniae, Chlamydia, and certain spirochetes. In clinical practice Erythromycin granules are often used as a substitute for patients with penicillin allergy to treat infections caused by sensitive bacteria, such as tonsillitis, pharyngitis, sinusitis, scarlet fever, cellulitis, diphtheria, syphilis, etc.; they can also prevent certain bacterial infections. In addition, Erythromycin granules can treat pneumonia, conjunctivitis and genitourinary infections caused by certain mycoplasma and chlamydia.