Guideline Statements

Guideline Statements

General Statements

Beta-lactam allergies, particularly allergies to penicillin, are over reported. Thorough beta-lactam allergy assessments are an important step in determining if a patient has a true allergy. Unnecessary avoidance of beta-lactam antibiotics and use of alternative non first line antibiotics has been associated with increased patient morbidity including decreased effectiveness, increased adverse effects, longer hospital stays, and increased C. difficile infection rates. Alternative non beta-lactam antibiotics are often more expensive and broader spectrum and exposure can lead to colonization and infection with resistant organisms.

Historically, cross reactivity rates between classes of beta-lactam antibiotics have been over estimated and based on older studies with flawed methodologies. However, as allergies have become better defined and the role of the antibiotics chemical structure on likelihood of cross reactivity is better understood, more recent data suggests cross reactivity between penicillins and other beta-lactams is much lower.

For patients in which a true penicillin or other beta-lactam allergy cannot be ruled out based on history and assessment, the below information can be used to aid in determining which beta-lactam may be safe to administer.


This information is not meant to replace clinical judgement or meant to be an antibiotic treatment guideline. The information is based on the most recent literature surrounding beta lactam cross reactivity and is meant as an aid in determining beta lactam alternatives with a low cross allergy risk.

It is important to note that new intolerances (i.e. any allergy or adverse reaction reported in a drug allergy field) can occur after 0.5 to 4% of all antimicrobial courses depending on the specific agent. Expect a higher incidence of new intolerances in patients with three or more prior medication intolerances. A thorough allergy assessment should always be conducted in any patient reporting an allergy.