Represcription of penicillin after allergic-like events

J Allergy Clin Immunol. 2004 Apr;113(4):764-70. doi: 10.1016/j.jaci.2003.11.032.


Objective: We sought to determine the frequency of represcription of penicillin to individuals with penicillin allergy and the risk of a second reaction in those who had a previous reaction.

Methods: A retrospective cohort study was conducted within the UK General Practice Research Database. All patients who had received a prescription for penicillin were identified. Within that source population, records of patients who had received at least 2 prescriptions for penicillin at least 60 days apart were selected and examined for allergic-like (hypersensitivity) events on the day of or within 30 days after a prescription.

Results: At least one prescription for penicillin was given to 3,375,162 patients. Of 6212 (0.18%) patients who experienced an allergic-like event after the initial prescription, 48.5% were given a second prescription compared with 59.8% of those without an initial allergic-like event (risk ratio, 0.81; 95% CI, 0.79-0.83). Two or more prescriptions for penicillin were given to 2,017,957 patients. Three thousand fourteen (0.15%) patients experienced an allergic-like event after the first prescription, and 57 (1.89%) of those had another event after the second prescription. The unadjusted odds ratio of an allergic-like event after the second prescription for those who experienced an allergic-like event after the first prescription, compared with those who had no initial event was 11.2 (95% CI, 8.6-14.6). Adjusting for confounding had no substantive effect on this result.

Conclusion: The risk of an allergic-like event after penicillin is markedly increased in those who have had a prior event, although the absolute difference is small (1.72%). Represcription of penicillin to such patients is more frequent than anticipated.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Cohort Studies
  • Drug Hypersensitivity / etiology*
  • Drug Prescriptions / statistics & numerical data*
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • Penicillins / adverse effects*
  • Recurrence
  • Retrospective Studies
  • Risk Factors


  • Penicillins