Aloe vera has been studied for its potential benefits in managing cold sores (herpes labialis), primarily due to its antiviral, anti-inflammatory, and wound-healing properties. Several in vitro studies have shown that Aloe vera extracts possess activity against herpes simplex virus type 1 (HSV-1), the primary cause of cold sores. For example, some laboratory experiments have demonstrated that components in Aloe vera gel may inhibit HSV-1 replication or reduce the cytopathic effects of the virus. Additionally, Aloe vera is well recognized for its soothing effects on skin and its ability to promote healing of minor wounds, which may help alleviate discomfort and accelerate recovery of lesions caused by cold sores.

However, clinical evidence in humans is limited. A small number of controlled studies have evaluated topical Aloe vera preparations for herpes lesions, with some finding modest improvements in healing time and symptom relief compared to control or placebo. The evidence is not robust or consistent enough to recommend Aloe vera as a primary treatment, but it does suggest some benefit in symptom management. Most health authorities and systematic reviews consider the evidence to be preliminary, and recommend further high-quality clinical trials.

In summary, Aloe vera's use for cold sores is supported by laboratory research and limited clinical studies, justifying a moderate evidence rating. While it may provide some relief, it should not replace standard antiviral therapies.