Background: Antibiotic resistance is an increasing problem globally, and is attracting more and more attention. According to WHO, it is one of the biggest threats to global health today. The development of resistance occurs naturally, but unnecessary use of broad spectrum antibiotics helps accelerate the process. In Norway the goal is to reduce both the total use of antibiotics and broad spectrum with 30 % by 2020. A big contribution to increased use of broad spectrum antibiotics is within patients claiming to be allergic to penicillin. Method: We performed a literature search in PubMed in April 2018 on systematic reviews, review, observational studies and clinical trials. English publications from the last 15 years that studied patients with suspected or documented penicillin allergy and then underwent allergy testing were included. Results: Our search gave 177 studies, and out of those, 7 met our inclusion criteria. 2 were systematic reviews and metaanalysis, 4 were original studies and 1 was a review. We then included other studies outside our original search to extend the task to also include immunological reactions, test methods and diagnostics, and cross reactions. Conclusions: There is an overdiagnosis of penicillin allergy. The amount of people having the diagnosis is too high compared to how many who actually have an allergy. When assessing allergy it is important to be aware of the different types of allergic reactions. One have to know which of the reactions you still can give penicillin and when one should give alternative antibiotic treatment. In addition, it is important to distinguish side effects from real allergic and life threatening reactions.