The best effect of Clarithromycin in a few days depends on the type of disease, individual condition and severity of infection, and cannot be generalized. Clarithromycin is a commonly used clinical antibiotic, pharmacologically its belongs to macrolide class and has a good therapeutic effect against Gram-positive bacteria, and also for Legionella, Mycoplasma, Chlamydia and Haemophilus influenzae. Clarithromycin can be used to treat infections of the digestive system, urinary system, and respiratory system. For mild common infections, the patient’s symptoms will be gradually relieved after 5-7 days of frequent use. For severe infections, the duration of use is about 10-14 days. If applied for anti-Helicobacter pylori treatment, the duration of its use is 2 weeks. A common side effect of clarithromycin during its application is gastrointestinal reactions such as nausea, vomiting, abdominal pain, etc. It is recommended to take the drug under the guidance of a clinician and to visit a hospital in time for any uncomfortable symptoms.