“…We identified 48 clinical trials investigating systemic tetracycline treatment efficacy in inflammatory acne, 11–58 29 trials investigating minocycline systemic treatment efficacy, 28,37,39,45,46,54,58–80 10 trials investigating doxycycline systemic treatment efficacy 8,9,20,62,68,69,81–84 and seven trials investigating lymecycline systemic treatment efficacy, 77,80,85–89 57 of which were included 8,9,12,14,16,17,19–21,23,25–38,41,42,44–52,54,56–58,62,66,69,71,72,75–81,83–88 . Trials were excluded for the following reasons: combination with other topical or systemic drug with antiacne efficacy, 18,53,55,64,68,73,74,82,89 use of obsolete drugs, 11,15,22 antibiotic treatment < 1 month prior to the study or selection of cases unresponsive to other antibiotics, 24,53,59,61,63,67,74 duplicate reports, 70 specific forms of acne (nodulocystic acne, 43,65 oil acne 40 ), cross‐over studies 13,18,39,60,63 …”