BACKGROUND: Helicobacter pylori eradication is a challenge in penicillin allergy. AIM: To assess the efficacy and safety of first-line and rescue treatments in patients allergic to penicillin. METHODS: Prospective multicenter study. Patients allergic to penicillin were given a first-line treatment comprising (a) 7-day omeprazole-clarithromycin-metronidazole and (b) 10-day omeprazole-bismuth-tetracycline-metronidazole. Rescue treatments were as follows: (a) bismuth quadruple therapy; (b) 10-day PPI-clarithromycin-levofloxacin; and (c) 10-day PPI-clarithromycin-rifabutin. Eradication was confirmed by (13)C-urea breath test. Compliance was determined through questioning and recovery of empty medication envelopes. Adverse effects were evaluated by questionnaires. RESULTS: In total, 267 consecutive treatments were included. (1) First-line treatment: Per-protocol and intention-to-treat eradication rates with omeprazole-clarithromycin-metronidazole were 59 % (62/105; 95 % CI 49-62 %) and 57 % (64/112; 95 % CI 47-67 %). Respective figures for PPI-bismuth-tetracycline-metronidazole were 75 % (37/49; 95 % CI 62-89 %) and 74 % (37/50; 95 % CI (61-87 %) (p < 0.05). Compliance with treatment was 94 and 98 %, respectively. Adverse events were reported in 14 % with both regimens (all mild). (2) Second-line treatment: Intention-to-treat eradication rate with omeprazole-clarithromycin-levofloxacin was 64 % both after triple and quadruple failure; compliance was 88-100 %, with 23-29 % adverse effects (all mild). (3) Third-/fourth-line treatment: Intention-to-treat eradication rate with PPI-clarithromycin-rifabutin was 22 %. CONCLUSION: In allergic to penicillin patients, a first-line treatment with a bismuth-containing quadruple therapy (PPI-bismuth-tetracycline-metronidazole) seems to be a better option than the triple PPI-clarithromycin-metronidazole regimen. A levofloxacin-based regimen (together with a PPI and clarithromycin) represents a second-line rescue option in the presence of penicillin allergy.