for people ages 18-70 (full criteria)
study started
completion around



Cephalosporin antibiotics are commonly used but can result in allergic reactions and anaphylaxis. There is no clear diagnostic approach for cephalosporin-allergic patients, and guidance for the use of other antibiotics in allergic patients is based on side chain chemical similarity and limited skin testing evidence. This project includes a clinical trial and mechanistic studies to optimize the approach to cephalosporin allergy and advance future diagnostics.



In the United States, beta-lactam antibiotics are the leading cause of allergic reactions. Cephalosporin antibiotics, in particular, are the most common cause of drug-induced anaphylaxis and perioperative allergy. For penicillin allergy, the mechanism of allergy and the antigenic determinants are known; validated penicillin skin testing followed by drug challenge has a 100% negative predictive value to exclude an immunoglobulin (Ig)E-mediated reaction. For cephalosporin allergy, the antigenic determinants and mechanism are not known, and skin testing is not validated. The diagnostic test characteristics of skin testing with native cephalosporins remain unclear with no sensitivity nor specificity reported. Although beta-lactam cross-reactivity has been hypothesized to be from the similarity of the R1 side chains, rather than the beta-lactam ring, cross-reactivity estimates among beta-lactams vary. Furthermore, it is not known whether the variance in cross-reactivity is due to true allergy versus sensitization based on positive skin testing, given that drug challenges were not performed on skin-test-positive patients. While an IgE mechanism is assumed for cephalosporin allergy and supported by skin testing that has been positive, the biology has yet to be characterized, and some cephalosporin anaphylaxis can occur on the first exposure, which is inconsistent with an IgE mechanism. Given the complexity of cephalosporin structures and potential epitopes, there may be several distinct biologic pathways involved in cephalosporin allergy. Future diagnostics in cephalosporin allergy are reliant on determination of these biological pathways and finding key haptens.


Current national practice guidelines related to cephalosporin allergy assessment are considered conditional and based on low-quality evidence. The overall goal is to identify the optimal diagnostic approach to cephalosporin allergy and determine beta-lactam cross-reactivity, while discovering the mechanism and antigenic determinants of cephalosporin allergy to advance future diagnostics. The investigators will do this through a clinical trial that will generate empirical evidence through novel trial procedures, double-blind skin testing, and double-blind placebo-controlled drug challenges. Specific aims are: 1) To determine the optimal approach to cephalosporin allergy evaluation; 2) To assess beta-lactam cross-reactivity in cephalosporin-allergic individuals; and 3) To investigate the antigenic determinants and mechanism of cephalosporin allergy.

Study Overview:

Enrolled and consented subjects will attend visit 1 for baseline screening, sample collection, double-blind skin testing to a beta-lactam panel, and a double-blind placebo-controlled challenge to their culprit cephalosporin antibiotic. Results of the culprit cephalosporin challenge determine subject's study timeline. Subjects confirmed as non-allergic to their culprit cephalosporin will return for visit 2 for venipuncture and blood collection, ending their participation in the study. Subjects who are confirmed as allergic to their culprit at visit 1 will return for three additional visits; visits 2 and 3 will include double-blind placebo-controlled challenges to a similar side chain and dissimilar side chain cephalosporin (as compared to the side chain of their culprit) to assess cross-reactivity. The order of these two challenges is randomized between visit 2 and 3, and the order of whether a similar or dissimilar side chain cephalosporin is challenged first (in visit 2) differentiates the comparator arms of this study. In visit 4, subjects from both comparator arms will undergo a double-blind placebo-controlled challenge to a penicillin to assess cross-reactivity between cephalosporins and penicillins. Completion of this penicillin challenge marks the end of participation for confirmed-allergic subjects. Venipuncture and sample collection will occur at each visit.


Drug Allergy, Cephalosporin Allergy, Drug Hypersensitivity, Antibiotic Allergy, Beta Lactam Adverse Reaction, Drug-Induced Anaphylaxis, Cephalosporin Reaction, Allergy, Antibiotic, Cephalosporin, Penicillin, Beta-lactam, Drug challenge, Skin testing, Adverse reaction, Anaphylaxis, Perioperative anaphylaxis, Hypersensitivity, Anti-Bacterial Agents, Amoxicillin, Cefazolin, Ceftriaxone, Penicillins, Ceftazidime, Cephalexin, Ampicillin, Cefepime, Cefuroxime, Cefuroxime axetil, Lactams, Cefdinir, Cephalosporins, Cefotaxime, Cefoxitin, Cefixime, beta-Lactams, Penicillin G, Penicillin G Benzathine, Penicillin G Procaine, Cefadroxil, Cefpodoxime, Cefaclor, Antitubercular Antibiotics, Beta Lactam Antibiotics, Histamine, Beta-lactam antibiotic (cefazolin, cefuroxime, cefotaxime, ceftazidime, ceftriaxone, cefepime, pre-pen, penicillin G, ampicillin, and histamine) double-blind skin testing, Similar cephalosporin first, Dissimilar cephalosporin first


You can join if…

Open to people ages 18-70

  1. Age 18-70 years old.
  2. Reaction history consistent with a potential immediate hypersensitivity reaction (pruritus, urticaria, erythema, angioedema, bronchospasm, wheezing, shortness of breath, and anaphylaxis) to cefazolin, ceftazidime, ceftriaxone, cefepime, cephalexin, cefaclor, cefadroxil, cefuroxime, cefpodoxime, cefdinir, or cefixime.
  3. English speaking or non-English speaking with translation services available.

You CAN'T join if...

  1. Severe concomitant medical condition (e.g., unstable coronary artery disease, congestive heart failure, severe chronic obstructive pulmonary disease, poorly controlled asthma, chronic renal failure, cirrhosis, or end-stage liver disease.)
  2. History of Clostridioides difficile infection
  3. Chronic spontaneous urticaria or systemic mastocytosis
  4. Incident reaction required cardiopulmonary resuscitation
  5. Reaction to 2 or more cephalosporin antibiotics
  6. Active infection or systemic antibiotic treatment within 7 days
  7. Treatment with systemic antihistamines or corticosteroids within 7 days
  8. Treatment with omalizumab or dupilumab within 60 days
  9. Significant immunosuppression

    10. Treatment with a beta-blocker or ACE inhibitor within 7 days 11. Use of investigational drugs within 60 days of participation 12. Abnormal vital signs or unstable physical exam at Visit 1 13. Prison or jail inmates, pregnant women, severe cognitive impairment 14. Current, diagnosed, mental illness or current, diagnosed, or self-reported drug or

    alcohol abuse that, in the opinion of the investigator, would interfere with the participant's ability to comply with study requirements

    15. Past or current medical problems or findings from physical examination or laboratory

    testing that are not listed above, which, in the opinion of the investigator, may pose additional risks from participation in the study, may interfere with the participant's ability to comply with study requirements or that may impact the quality or interpretation of the data obtained from the study.

    16. Inability or unwillingness of a participant to give written informed consent or comply

    with study protocol


  • University of California, San Francisco
    San Francisco California 94143 United States
  • University of Texas Southwestern Medical Center
    Dallas Texas 75390 United States


not yet accepting patients
Start Date
Completion Date
Massachusetts General Hospital
Phase 2 research study
Study Type
Expecting 300 study participants
Last Updated