Immediate allergic reactions to amoxicillin

Allergy. 1994 May;49(5):317-22. doi: 10.1111/j.1398-9995.1994.tb02275.x.


A large group of patients with suspected allergic reactions to beta-lactam antibiotics was evaluated. A detailed clinical history, together with skin tests, RAST (radioallergosorbent test), and controlled challenge tests, was used to establish whether patients allergic to beta-lactam antibiotics had selective immediate allergic responses to amoxicillin (AX) or were cross-reacting with other penicillin derivatives. Skin tests were performed with benzylpenicilloyl-poly-L-lysine (BPO-PLL), benzylpenicilloate, benzylpenicillin (PG), ampicillin (AMP), and AX. RAST for BPO-PLL and AX-PLL was done. When both skin test and RAST for BPO were negative, single-blind, placebo-controlled challenge tests were done to ensure tolerance of PG or sensitivity to AX. A total of 177 patients were diagnosed as allergic to beta-lactam antibiotics. We selected the 54 (30.5%) cases of immediate AX allergy with good tolerance of PG. Anaphylaxis was seen in 37 patients (69%), the other 17 (31%) having urticaria and/or angioedema. All the patients were skin test negative to BPO; 49 of 51 (96%) were also negative to MDM, and 44 of 46 (96%) to PG. Skin tests with AX were positive in 34 (63%) patients. RAST was positive for AX in 22 patients (41%) and to BPO in just 5 (9%). None of the sera with negative RAST for AX were positive to BPO. Challenge tests with AX were performed in 23 subjects (43%) to establish the diagnosis of immediate allergic reaction to AX, and in 15 cases (28%) both skin test and RAST for AX were negative. PG was well tolerated by all 54 patients. We describe the largest group of AX-allergic patients who have tolerated PG reported so far. Diagnosis of these patients can be achieved only if specific AX-related reagents are employed. Further studies are necessary to determine the exact extent of this problem and to improve the efficacy of diagnostic methods.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Amoxicillin / adverse effects*
  • Ampicillin
  • Anaphylaxis / chemically induced
  • Anaphylaxis / diagnosis
  • Anaphylaxis / immunology
  • Angioedema / chemically induced
  • Angioedema / diagnosis
  • Angioedema / immunology
  • Cross Reactions
  • Drug Eruptions / diagnosis
  • Drug Eruptions / etiology
  • Drug Eruptions / immunology
  • Female
  • Humans
  • Hypersensitivity, Immediate / chemically induced*
  • Hypersensitivity, Immediate / diagnosis
  • Hypersensitivity, Immediate / immunology
  • Male
  • Middle Aged
  • Penicillin G / analogs & derivatives
  • Radioallergosorbent Test
  • Skin Tests
  • Urticaria / chemically induced
  • Urticaria / diagnosis
  • Urticaria / immunology


  • Ampicillin
  • Amoxicillin
  • benzylpenicilloic acid
  • Penicillin G