There is no specific time for doxycycline tablets to treat acne, the key depends on the severity of acne and the effect of treatment, the general treatment time is about 4 weeks. Acne is a chronic inflammatory disease of the skin, which can be manifested in the clinic as pimples, papules, pustules, cysts and nodules, etc. Acne at different periods of time has different treatment methods and effects. Pimples are one of the earliest manifestations of acne and are usually treated with topical medications. Cystic acne and nodular acne, which belong to more serious acne, when choosing doxycycline tablets for treatment, the treatment time is generally 4 weeks for a course of treatment, and may need to increase the course of treatment according to the changes in the condition. Adverse effects of doxycycline tablets are mainly manifested as nausea, vomiting, abdominal pain, diarrhea, hepatotoxicity and hemolytic anemia, etc., adverse reactions must be discontinued in time. People who are allergic to the components of the drug, children under 8 years of age, pregnant women and other groups need to be prohibited. In order to ensure the safety and effectiveness of the drug, when choosing the time of treatment, be sure to strictly follow the doctor’s instructions.