| Level I | Good quality evidence |
Systematic review of RCTs with consistent findings High quality individual RCT |
| Level II |
Limited quality patient orientated evidence |
Systematic review of lower quality studies or studies with inconsistent findings Low quality clinical trial Cohort studies Case-control studies |
| Level III | Other |
Consensus guidelines, extrapolations from bench research, usual practice, opinion, disease-oriented evidence (intermediate or physiologic outcomes only), or case series |
[17] Promethazine, IV/ cetirizine, oral: Sheikh A, ten Broek Vm, Brown SG, Simons FE. H1-antihistamines for the treatment of anaphylaxis with and without shock. Cochrane Database Syst Rev. 2007 Jan 24;(1):CD006160. https://www.ncbi.nlm.nih.gov/pubmed/17253584
Promethazine, IV/ cetirizine, oral: Resuscitation Council of South Africa, Emergency Management of Anaphylaxis Guidelines, 2015. https://resus.co.za/anaphylaxis/
Promethazine, IV/ cetirizine, oral: Fernando SL, Broadfoot AJ. Ondansetron anaphylaxis: a case report and protocol for skin testing. Br J Anaesth. 2009 Feb;102(2):285-6. https://www.ncbi.nlm.nih.gov/pubmed/19151059