Methohexital is a barbiturate derivative used for brief surgical procedures.
Reported incidence ranges from 1/7000 to 0/23000.
0.2% in dentistry.
No deaths have been reported.
Clinical manifestations
Essentially cutaneous, mucosal (pruritus, urticaria, rash, edema) and cardiovascular.
Respiratory (bronchospasm) and digestive symptoms are unusual.
Symptoms are usually delayed (a few minutes after injection).
Diagnostic methods
Non specific histamine-release.


  1. Liu L.M, Liu P.L, Moss J, "Severe histamine-mediated reaction to rectally administered methohexital", Anesthesiology, 1984 ; 61 (1): 95-7
  2. McDonald D, "Methohexitone in dentistry. Scientific results of 4379 administrations. 5: complications", Dent. Anaesth. Sedat., 1982 ; 11 (2): 51-7
  3. Harrison G.R, Thompson I.D, "Adverse reaction to methohexitone and gallamine", Anaesthesia, 1981 ; 36 (1): 40-4
  4. Driggs R.L, O’Day R.A, "Acute allergic reaction associated with methohexital anesthesia: report of six cases" J. Oral. Surg., 1972 ; 30: 906-9.

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.