Study	Reason for exclusion
Blanca‐Gomez 1984	This was not a RCT.
Bleehen 1987	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Commens 1978	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Cook 1979	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Cook 1983	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Diller 1983	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Harvey 1981	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Kaur 1981	This was a cross‐over study. No data was available for each participant at each intervention period to permit a paired analysis of the within‐person effects of the interventions as recommended by Elbourne 2002.
Matthews 1979	This was a cross‐over study. No data was available for each participant at each intervention period to permit a paired analysis of the within‐person effects of the interventions as recommended by Elbourne 2002.
Michell 1980	This was not a RCT.
Moscati 1990	This was reported as a RCT, but randomisation was by alternation (quasi‐randomised controlled clinical trial).
Paul 1986	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Paul 1987	The study included healthy subjects.
Sharpe 1993	This was a cross‐over study. No data was available for each participant at each intervention period to permit a paired analysis of the within‐person effects of the interventions as recommended by Elbourne 2002.
Simons 1995	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Wan 2009	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.
Wozel 1990	This was a RCT, but participants had chronic urticaria and interventions included H2‐antihistamines and H1‐antihistamines. This study will be included in the Cochrane review on H1‐antihistamines for chronic urticaria.

RCT = Randomised controlled trial

ED = Emergency Department