Cephalexin-induced bradycardia in a young healthy woman

Mahmoud Abdelnabi MD, MSc, Juthipong Benjanuwattra MD, Sean Noormohamed Lee MD, Saif El Nawaa MD

Corresponding author: Mahmoud Abdelnabi
Contact Information: Mahmoud.abdelnabi@ttuhsc.edu
DOI: 10.12746/swrccc.v10i45.1095

CASE

A 32-year-old woman with a history of gastric bypass surgery presented with a 2-day history of nausea, vomiting, light-headedness, and chest tightness, which coincided with starting cephalexin for 4 days for an ingrown nail. Her electrocardiogram showed sinus bradycardia at 40 beats/minute with no evidence of atrioventricular (AV) block (Figure). She was hospitalized under observation, and the cephalexin was stopped. Her laboratory workup, including electrolytes and TSH, and her echocardiogram were unremarkable. Continuous telemetry revealed bradycardia ranging from 40–60 beats/minute with no AV block. Her treadmill stress test suggested chronotropic incompetence. She was asymptomatic during a 48-hour observation period, and she was discharged and scheduled for a follow-up. Two weeks later, she was able to reach 100% of maximum heart rate suggesting chronotropic incompetence reversal following cephalexin stoppage.


Figure 1

Figure. Sinus bradycardia 40 beats/minute with no evidence of atrioventricular (AV) block.


DISCUSSION

Macrolides and fluoroquinolones are associated with adverse cardiac effects, such as prolonged QT and torsades de pointes.1 Bradycardia is rarely reported as a side effect of antibiotic therapy. In a phase IV clinical trial analyzing cephalexin side effects, 12,600 patients reported having side effects; 102 patients (0.81%) had bradycardia. Bradycardia was mainly reported in female patients older than 60, who took cephalexin for less than 1 month.2 Physicians should have a high index of suspicion for the possible side effects after antibiotic therapy for early detection and management of potentially reversible complications.

Consent: Informed written consent was obtained from the patient.

Keywords: Bradycardia, side effects, cephalexin


REFERENCES

  1. Lu ZK, Yuan J, Li M, Sutton SS, et al. Cardiac risks associated with antibiotics: azithromycin and levofloxacin. Expert opinion on drug safety. 2015 Feb 1;14(2):295–303.
  2. Keflex and Bradycardia, a phase IV clinical study of FDA data - eHealthMe [Internet]. Ehealthme.com. 2022 [cited 22 September 2022]. Available from: https://www.ehealthme.com/ds/keflex/bradycardia/


Article citation: Abdelnabi M, Benjanuwattra J, Lee SN, El Nawaa S. Cephalexin-induced bradycardia in a young healthy woman. The Southwest Respiratory and Critical Care Chronicles 2022;10(45):83–84
From: Departments of Internal Medicine (MA, JB, SEN) and Anaesthesiology (SNL), Texas Tech University Health Sciences Center, Lubbock, Texas
Submitted: 9/22/2022
Accepted: 9/24/2022
Conflicts of interest: none
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