The purpose of this study is to estimate the prevalence of penicillin allergy, evaluate the diagnostic value of the allergologic work-up used in the study, and the health effects of penicillin allergy.

Penicillin allergy is the most common of self-reported drug allergies and un-verified penicillin allergy is a significant and growing public health problem. 10% of all patients report penicillin allergy. However, there is large discrepancy between reported penicillin allergy and true allergy. Despite its high prevalence, greater than 90% of such patients are in fact able to tolerate the medication without allergic reactions.

In this study patients having a penicillin allergy label will be investigated to confirm or to exclude the allergy diagnosis. The diagnostic value of the allergen test panel and the allergologic work-up will be evaluated. Clinical parameters as well as immunological will be assessed.

Inclusion Criteria:

• Adult patients who are referred to the department of Pulmonary medicine with clinical history suspected of having penicillin allergy.
• The control group will be healthy adult volunteers with no history of any personal or family history of drug allergy, atopy, inflammatory or autoimmune diseases.

Exclusion Criteria:

• Systemic reactions such as DRESS, any internal organ involvement
• Clinical history of Type II-III hypersensitivity reaction
• Severe Type IV hypersensitivity reaction such as Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS, vasculitis, acute generalized exanthematous pustulosis
• Chronic idiopathic urticaria on antihistamine maintenance treatment/anti-IgE treatment
• Medication which can affect the test outcome
• Active signs of an underlying disease such as uncontrolled asthma
• Cardiac disease with increased risk of serious anaphylaxis
• Pregnancy/Breastfeeding
• Reaction within the last 4-6 weeks