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Injection of adrenaline in acute allergic reaction: Do the thighs look better than the deltoid? – Read the evidence.

Three Part Question

In [patients with acute allergic reaction] do [the injection of adrenaline given in vastus lateralis as compared to deltoid] work [faster and have better effect?]

Clinical Scenario

A 20 year Arabian girl presents to emergency department having stung by a bee in her garden. She has urticaria and lip swelling. You offer her injection of adrenaline into her thigh, but she demands female doctor and adds that she will take injection only in her arm. You wonder whether there is any difference in the absorption and effect of adrenaline between the thigh and the deltoid.

Search Strategy

Medline 1950 to 11/11/2008; EMBASE 1974 to 11/11/2008
(exp Anaphylaxis/ or or anaphyla$.mp. or exp Hypersensitivity/ or allergic or or allerg$.mp.or (acute adj allergic adj reaction).mp) AND ( or exp Epinephrine/ or adrenalin$.mp. or epinephrin$.mp.) AND ( or exp Thigh/ or (lateral adj thigh).mp. or (vastus adj lateralis).mp. or or exp Arm/ or (upper adj arm).mp. or or exp Deltoid Muscle/) limit to (english language and humans)

Search Outcome

Medline : 15 papers were found
EMBASE : 26 papers were found
One paper was found be relevant.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Simons et al
13 healthy allergic young men aged 18-35 years of age.Prospective, randomized, blinded, placebo-controlled, 6-way crossover study.Lateral thigh is superior to arm in plasma levels over time Mean plasma epinephrine concentration Cmax was 9 to 13 time higher in lateral thigh than armSmall number of subjects. Subjects were healthy \"allergic\" young men who were not in anaphylaxis. Injection in the arm was subcutaneous or intramuscular where as in the thigh was only IM.


It is surprising that subcutaneous injection of epinephrine was recommended for almost a century, despite the fact that adrenaline is a strong vasoconstrictor. The blood flow to vastus lateralis is much higher compared that of the deltoid. This is likely the fact that has led to higher adrenaline concentration after injection into lateral thigh as compared to arm. A second peak was also observed at about forty minutes, which may be attributed to rebound endogenous release of epinephrine, which is well known phenomenon (1). The weaknesses named above were replied to by the authors in a reply to a correspondence by Dr Chowdhury and Meyer* in which it was stated: “Although we would prefer to investigate epinephrine in terms of clinical outcomes in patients during anaphylaxis, for reasons that we have delineated previously it is unlikely that a prospective, randomized, double-blinded, controlled trial of epinephrine will ever be conducted during the first-aid treatment of anaphylaxis. Studies of the clinical pharmacology of epinephrine in individuals not experiencing anaphylaxis are preferable to no studies at all” In our randomized, blinded, placebo-controlled crossover study of intramuscular (IM) versus SC epinephrine in adults, we tested injection routes and sites that are used in clinical practice. We did not include SC injection of epinephrine into the thigh in our study design, because the thigh is not a recommended site for SC epinephrine injection6; furthermore, it is not practical to use this route.

Clinical Bottom Line

Lateral thigh leads to quicker and higher plasma levels of epinephrine as compared to deltoid for the same dose of adrenaline. Level of evidence: 2c Grade of recommendation:C Level of evidence: 2c Grade of recommendation: C


  1. Simons F E R, Xiaochen Gu, Simons K J. Epinephrine absorption in adults:Intramuscular versu subcutaneous injection., J Allerg Clin Immunol 2001;108:871-873.
  2. Chowdhury BA, Meyer RJ. Correspondence to Editor,Intramuscular versus subcutaneous injection of epinephrine in the treatment of anaphylaxis. Clin Immunol. 2002 Apr;109(4):720; author reply 720-1.