| 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 |
[6] Non-sedating antihistamines, oral: Howarth PH, Stern MA, Roi L, Reynolds R, Bousquet J. Double-blind, placebo-controlled study comparing the efficacy and safety of fexofenadine hydrochloride (120 and 180 mg once daily) and cetirizine in seasonal allergic rhinitis. J Allergy ClinImmunol. 1999;104(5):927-933. https://www.ncbi.nlm.nih.gov/pubmed/10550734
Non-sedating antihistamines, oral: Olasińska-Wiśniewska A , Olasiński J, Grajek S. Cardiovascular safety of antihistamines. Postep Derm Alergol. 2014, 3: 182–186. https://www.ncbi.nlm.nih.gov/pubmed/25097491
Non-sedating antihistamines, oral: National Department of Health: Affordable Medicines, EDP-Adult Hospital level. Medicine Review: Non-sedating antihistamines for persistent allergic rhinitis, 23 November 2017. http://www.health.gov.za/
Cetirizine, oral: Contract circular HP 09-2016SD.