Amoxicillin renal toxicity: how often does it occur?

To determine the incidence of renal symptoms associated with amoxicillin, a retrospective review of exposures to amoxicillin in children younger than 6 years as reported to the National Poison Data System was done.

All ingestions of amoxicillin without coingestants in humans younger than 6 years reported to the National Poison Data System from 2004 through 2008 were analyzed. Data included age, sex, management site, outcome, symptoms, amount ingested, certainty of amount, chronicity, weight, and therapy. The study was approved by the institutional review board. Descriptive statistics were used to characterize the data.

A total of 14,717 cases were identified. Related renal symptoms occurred in 5 patients (0.03%). In 1687 patients (9.6%), the total amount (in milligrams) was documented, and the median amount ingested was 1000 mg. In patients with a known amount (in milligrams) along with the child's weight (n = 1356), the median amount was 82.6 mg/kg. In this group, 213 ingested greater than 250 mg/kg (range, 251.4-1531.1 mg/kg; median, 366.5 mg/kg). Treatment sites for this group included the following: treated in the home, 129 (60.6%); treated and released from an health care facility, 63 (29.6%); treated while admitted, 2 (0.9%); refused a referral, 7 (3.3%); lost to follow-up, 9 (4.2%); and managed at other sites, 3 (1.4%). Within this group, 94 patients (44.1%) were followed up to a definitive outcome: 77 (81.9%) had no effect, 15 (16.0%) had minor symptoms, and 2 (2.1%) had moderate symptoms.

Although renal toxicity may occur with amoxicillin ingestions, it is rare and does not seem to be dose related.