Adrenaline and non-life threatening allergic reactions

Editor—The life saving effects of adrenaline in severe allergic reactions are well established, so Johnston et al's lesson of the week cautioning against using adrenaline in “non-life threatening” conditions is worrying.¹,² Anaphylaxis or angioedema of the upper airway is life threatening, and avoiding or delaying appropriate treatment is clearly associated with adverse outcomes, including death.³

We question Johnston et al's interpretation of their two case reports.

In the first case the association between the episode of angina and the administration of adrenaline is not clear, especially given the patient's established heart disease. Moreover, in acute settings angioedema affecting the tongue may not be easily discerned as benign. In this case regular antihistamines are clearly indicated as long term treatment rather than episodic adrenaline, which still might provide effective emergency treatment.

The second case should not be used as evidence. To caution against safe, lifesaving treatment on the basis of the adverse effects of an incorrect dose of drug given through an incorrect route at an inappropriate dilution is inappropriate. Adverse effects from the use of undiluted (1:1000) adrenaline administered intravenously are well described in the literature and in clinical practice guidelines. Doctors choosing the intravenous route for adrenaline administration should be aware of this.⁴,⁵

Conversely, intramuscular adrenaline (1:1000) in doses of 0.01 mg/kg to a maximum of 0.4 mg is well established as safe, even in cases without anaphylaxis, and is not associated, to our knowledge, with cardiac toxicity. Practitioners specialising in the treatment of allergic conditions should be clearly stating the dangers of intravenous adrenaline while safeguarding effective treatment in patients with life threatening allergic reactions.