I. Antibiotics are an effective treatment for moderate and severe acne Oral antibiotics are one of the effective treatments for acne, especially for moderate and severe acne. Among the many colonizing microorganisms, including Staphylococcus epidermidis, Propionibacterium acnes, Malassezia and other gram-negative bacilli, only live Propionibacterium acnes has a clear association with increased inflammatory response to acne, so it is important to select antibiotics that are sensitive to Propionibacterium acnes. In addition to the inflammation caused by infection, immune and non-specific immune responses are also involved in the process of inflammatory damage in acne. Therefore, antibiotics that both inhibit the propagation of Propionibacterium acnes and take into account the non-specific anti-inflammatory effects should be given priority. Second, how to choose antibiotics? Combining the above factors with the pharmacokinetics of antibiotics, especially the selective distribution of seborrheic sites, tetracyclines should be preferred, followed by macrolides, others such as sulfamethoxazole-methoprene (cotrimoxazole) and metronidazole can also be used as appropriate, but β-lactam antibiotics should not be chosen. Among the tetracyclines, 1st generation tetracyclines such as tetracycline are poorly absorbed orally and have low sensitivity to Propionibacterium acnes; 2nd generation tetracyclines such as minocycline, doxycycline and lymetetracycline should be preferred, and the two should not be substituted for each other. For systemic infections currently important or commonly used antibiotics such as clarithromycin, roxithromycin, and levofloxacin are avoided. Third, the use of antibiotics should be standardized Because antibiotics for acne mainly inhibit the reproduction of Propionibacterium acnes, rather than non-specific anti-inflammatory effects, it is important to prevent or slow down the development of resistance in Propionibacterium acnes, which requires the use of antibiotics for acne should standardize the dosage and course of medication. Usually, the dose of minomycin and doxorubicin is 100-200mg/d, which can be taken orally once or in 2 doses, tetracycline 1.0g/d, taken orally in 2 doses on an empty stomach, and erythromycin 1.0g/d, taken orally in 2 doses. The course of treatment is 6-12 weeks. IV. How to avoid or reduce the development of drug resistance? Antibiotic treatment of acne should pay attention to how to avoid or reduce the emergence of drug resistance. These include: ① Avoid using them alone to treat acne, especially for long-term topical application; ② Treatment should be started in adequate doses and should not be reduced for maintenance once effective; ③ When there is no efficacy after 2-3 weeks of treatment, discontinue or switch to other antibiotics in a timely manner, and pay attention to patient compliance and differentiate between Gram-negative bacterial folliculitis; ④ Ensure an adequate course of treatment and avoid intermittent use; ⑤ Propionibacterium acnes is a parasitic bacteria of normal skin. Treatment is aimed at effectively inhibiting its reproduction rather than achieving complete elimination. Therefore, it is not possible to increase the dose or extend the course of treatment without principle, let alone as a maintenance treatment or even as a measure to prevent recurrence; ⑥The drug resistance of Propionibacterium acnes can be monitored if conditions permit, so as to guide the rational clinical use of drugs. V. Adverse reactions to oral antibiotics The treatment should pay attention to the adverse reactions to drugs, including the more common gastrointestinal reactions, drug rash, liver damage, photosensitivity reactions, vestibular involvement (such as dizziness, vertigo) and benign intracranial pressure elevation syndrome (such as headache). Rare adverse reactions include lupus-like syndrome, especially when applying minomycin, which should be used with caution or prohibited in patients with long-term alcohol consumption, hepatitis B, and photosensitive dermatitis. Tetracyclines should not be used in pregnant women and children under 16 years of age. Dividing the daily dose of minomycin into oral doses or using the extended-release dosage form once a night may partially reduce adverse reactions. Discontinue the drug promptly in case of serious adverse reactions or if the patient cannot tolerate it and treat the symptoms. Both macrolides and tetracyclines are prone to drug interactions, and attention should be paid to drug interactions when combined with other systemic drug therapy.