Table 1.

Overview of systemic antibiotic regimens in clinical studies.

References	Study Design (Level of Evidence, Oxford Criteria [84])	Treatment Regimen	Efficacy Data/Results
Tetracyclines
Jemec et al., 1996 [85]	randomized double-blind trial (n = 46) (evidence level: 1b)	top. clindamycin (0.1%) b.i.d. vs. tetracycline 500 mg b.i.d.	-no significant differences between treatment groups
Vural et al., 2019 [86]	retrospective analysis of different HS treatments (n = 139) (evidence level: 4)	doxycycline 100 mg b.i.d. for 3 months	-HiSCR achieved in 60% -doxycycline as preferred treatment regimen in Hurley stage I/II
Jørgensen et al., 2021 [70]	prospective follow-up study (n = 108) (evidence level: 2b)	tetracycline 500 mg b.i.d. (n = 32) vs. doxycycline 100 mg b.i.d. (n = 31) vs. lymecycline 300 mg b.i.d. (n = 45) median treatment duration: 3.2 months	-significant clinical improvements (reductions of HSS) in approx. 30%; -no significant differences between treatment groups (greatest HSS reduction observed in tetracycline group)
Armyra et al., 2017 [87]	prospective study/case series (n = 20) (evidence level: 4)	minocycline 100 mg q.d. + colchicine 0.5 mg b.i.d. for 3 months followed by colchicine 0.5 mg b.i.d. for 6 months	-significant clinical improvements (HS-PGA and DLQI)
Clindamycin–Rifampicin Combination Therapy
Yao et al., 2021 [71]	prospective open-label study (n = 56) (evidence level: 4)	clindamycin 300 mg b.i.d. + rifampicin 300 mg b.i.d. for 10 weeks	-at 6 month follow-up: overall response rate 79.6%; HSS50 37%; HSS100 13% -Side effects 55.6% (esp. gastrointestinal)
van der Zee et al., 2009 [73]	retrospective study (n = 34) (evidence level: 4)	clindamycin 600 mg b.i.d. + rifampicin 600 mg b.i.d. varying treatment duration (<10 weeks/>10 weeks)	-overall response rate 82.4%; partial remission 35.3%; total remission 47.1% -side effects 38.2% (esp. gastrointestinal)
Gener et al., 2009 [72]	retrospective study (n = 116) (evidence level: 4)	clindamycin 300 mg b.i.d. + rifampicin 600 mg q.d. for 10 weeks	-significant reduction of Sartorius score; complete remission in 11% -significant down-staging (Hurley) and reduction of pain
Mendonça et al., 2006 [74]	retrospective study (n = 14) (evidence level: 4)	clindamycin 300 mg b.i.d. + rifampicin 300 mg b.i.d for 10 weeks	-overall response rate 82%; complete remission 66.7%
Intensified Antibiotic Treatments
Join-Lambert et al., 2016 [81]	retrospective study (n = 30) (evidence level: 4)	ertapenem 1 g iv. q.d. for 6 weeks followed by antibiotic consolidation treatment (rifampicin, moxifloxacin, metronidazole)	after 6 weeks (ertapenem): -significant reduction of median Sartorius score -clinical remission in 67%/26% in Hurley stage I/II after 6 months (consolidation): -further significant clinical improvement -clinical remission 100%/96%/27% in Hurley stage I/II/III
Join-Lambert et al., 2011 [79]	retrospective study (n = 28) (evidence level: 4)	rifampicin 10 mg/Kg q.d. + moxifloxacin 400 mg q.d. + metronidazole 500 mg t.i.d. for 6 weeks *, followed by consolidation with rifampicin + moxifloxacin for ≥6 weeks	-complete remission 57% (esp. in Hurley I/II) -most common side effects: gastrointestinal symptoms 64%; vaginal candidiasis 35% (of female pat.)

* In 14 patients initiation therapy with ceftriaxone 1 g iv. q.d. + metronidazole 500 mg t.i.d. for 2 weeks due to severe inflammation.