Abstract: A total of 43 trials (35 RCTs and eight qRCTs) with 7465 participants were identified. Twenty-two trials with 5546 participants were involved in prevention of Aloe vera for phlebitis, and a further 21 trials with 1919 participants were involved in the treatment of phlebitis. The included studies compared external application of Aloe vera alone or plus non-Aloe vera interventions with no treatment or the same non-Aloe vera interventions. The duration of the intervention lasted from one day to 15 days. Most of the included studies were of low methodological quality with concerns for selection bias, attrition bias, reporting bias and publication bias. The effects of external application of fresh Aloe vera on preventing total incidence of phlebitis varied across the studies and we did not combine the data. Aloe vera reduced the occurrence of third degree phlebitis (RR 0.06, 95% CI 0.03 to 0.11, P < 0.00001) and second degree phlebitis (RR 0.18, 95% CI 0.10 to 0.31, P < 0.00001) compared with no treatment. Compared with external application of 75% alcohol, or 33% MgSO4 alone, Aloe vera reduced the total incidence of phlebitis (RR 0.02, 95% CI 0.00 to 0.28, P = 0.004 and RR 0.43, 95% CI 0.24 to 0.78, P = 0.005 respectively) but there was no clear evidence of an effect when compared with 50% or 75% MgSO4 (total incidence of phlebitis RR 0.41, 95% CI 0.16 to 1.07, P = 0.07 and RR 1.10 95% CI 0.54 to 2.25, P = 0.79 respectively; third degree phlebitis (RR 0.28, 95% CI 0.07 to 1.02, P = 0.051 and RR 1.19, 95% CI 0.08 to 18.73, P = 0.9 respectively; second degree phlebitis RR 0.68, 95% CI 0.21 to 2.23, P = 0.53 compared to 75% MgSO4) except for a reduction in second degree phlebitis when Aloe vera was compared with 50% MgSO4 (RR 0.26, 95% CI 0.14 to 0.50, P < 0.0001). For the treatment of phlebitis, Aloe vera was more effective than 33% or 50% MgSO4 in terms of both any improvement (RR 1.16, 95% CI 1.09 to 1.24, P < 0.0001 and RR 1.22, 95% CI 1.16 to 1.28, P < 0.0001 respectively) and marked improvement of phlebitis (RR 1.97, 95% CI 1.44 to 2.70, P < 0.001 and RR 1.56, 95% CI 1.29 to 1.87, P = 0.0002 respectively). Compared with 50% MgSO4, Aloe vera also improved recovery rates from phlebitis (RR 1.42, 95% CI 1.24 to 1.61, P < 0.0001). Compared with routine treatments such as external application of hirudoid, sulphonic acid mucopolysaccharide and dexamethasone used alone, addition of Aloe vera improved recovery from phlebitis (RR 1.75, 95% CI 1.24 to 2.46, P = 0.001) and had a positive effect on overall improvement (marked improvement RR 1.26, 95% CI 1.09 to 1.47, P = 0.0003; any improvement RR 1.23, 95% CI 1.13 to 1.35, P < 0.0001). Aloe vera, either alone or in combination with routine treatment, was more effective than routine treatment alone for improving the symptoms of phlebitis including shortening the time of elimination of red swelling symptoms, time of pain relief at the location of the infusion vein and time of resolution of phlebitis. Other secondary outcomes including health-related quality of life and adverse effects were not reported in the included studies. There is no strong evidence for preventing or treating infusion phlebitis with external application of Aloe vera. The current available evidence is limited by the poor methodological quality and risk of selective outcome reporting of the included studies, and by variation in the size of effect across the studies. The positive effects observed with external application of Aloe vera in preventing or treating infusion phlebitis compared with no intervention or external application of 33% or 50% MgSO4 should therefore be viewed with caution.

Plain-language summary: This review examined 35 randomised controlled trials and eight quasi-randomised controlled trials with 7465 participants. Twenty-two trials with 5546 participants were involved in looking at prevention of phlebitis with Aloe vera, and a further 21 trials with 1919 participants were involved in looking at Aloe vera for the treatment of phlebitis. The included trials mainly compared external application of fresh Aloe vera alone or with another non-Aloe vera treatment such as a wet compress of 75% alcohol or 33%, 50% or 75% MgSO4 with no treatment or the same non-Aloe vera treatment. The duration of intervention lasted from one day to 15 days. Most of the included studies were of low methodological quality with concerns for selection bias, attrition bias, reporting bias and publication bias. The incidence of phlebitis at varying degrees of severity as well as the resolution rate and level of improvement of phlebitis were investigated. The available evidence suggests that external application of fresh Aloe vera alone or combined with other non-Aloe vera treatment may be effective for the prevention and treatment of infusion phlebitis resulting from the intravenous therapy. The conclusions should be cautiously interpreted due to the low methodological quality of the included trials.