Doxycycline Hydrochloride after taking how long can the sun, there is no uniform regulations, do not take the drug directly exposed to sunlight or ultraviolet rays, if erythema, red rash during the use of the drug need to stop using the drug. Doxycycline hydrochloride is a tetracycline antibiotic, this drug can be used for rickettsial disease, Mycoplasma spp. and Chlamydia spp. infections, regression fever, cholera plague, soft chancre, rabbit fever, brucellosis and many other diseases. Doxycycline hydrochloride has photosensitivity, how long can patients sunbathe after using the drug, there is no authoritative information to stipulate, individual sun exposure will appear allergic reactions, try not to let the skin directly exposed to sunlight or ultraviolet light, avoid prolonged sunbathing, if there is a rash, erythema, should be immediately discontinued during the use of the drug. Doxycycline hydrochloride may cause gastrointestinal reactions such as nausea and vomiting, and hepatotoxicity in a small number of patients, and even occasionally cause thrombocytopenia, headache, secondary infections, dry mouth and pharyngitis and other side effects. Doxycycline hydrochloride should not be used by people who are allergic to tetracycline, pregnant women, or children under 8 years of age. Long-term use of the drug requires checking of liver function and blood routine, and those with secondary infections need to stop the drug for treatment. This drug should be used under the guidance of a doctor, and individuals should not use it indiscriminately.