Zinc is essential to the activity of many enzymes in the human body, including those involved in replicating genetic material. Zinc supplementation helps to replenish stores used up during tissue repair.1Godfrey and colleagues studied the effectiveness of a zinc oxide/glycine cream in early HSV-1 lesions, in which 59 subjects were screened and 46 were evaluable and enrolled within 24 hours of initial prodromal symptoms.1The subjects were randomized to either a zinc oxide/glycine cream (n=24) or base cream matched placebo (n=22). The cream was applied initially by subjects at study enrollment and then no more than every two hours (with a minimum of three times per day). Time to lesion healing was significantly shorter in zinc-treated subjects compared with placebo (5.0 ± 1.7 days versus 6.5 ± 2.5 days, P=0.018). The zinc cream was associated with more topical adverse events (burning and itching) compared with placebo. It was stated that signs and symptoms of the cold sores were decreased in the zinc group, but statistical significance was not provided. It is likely that the difference in adverse effect profiles of the zinc and placebo creams distorted differences in clinical outcomes.1 Although this is only one study, and it was relatively small, it does support the use of zinc oxide cream in the treatment of cold sore outbreaks.
In vitro and animal studies have shown that the essential amino acid L-lysine decreases herpetic viral load and shortens healing time, but the mechanism of these effects has not been elucidated.2Singh and colleagues studied the effects of an L-lysine cream on 30 subjects aged 18 to 65 years from a single site who presented with cold sores and symptoms for less than 24 hours. Subjects were treated with the L-lysine cream (without a placebo group), had lesions photographed, and kept symptom diaries for up to 21 days. Lesions healed in all subjects within 11 days (average healing time of 4.5 ± 2.8 days, based on post-hoc analysis of data provided in the published monograph). Symptom resolution was statistically significant (P<0.001) by three days and six days of treatment.2 Although data from these studies appear to provide clinical utility, there are cautions to be noted. First, these studies were not placebo controlled. Although the time to resolution was similar to that seen with other active agents studied, there is insufficient information included in these studies to allow for cross study comparisons. Secondly, and more importantly, the L-lysine cream also contained zinc, lithium carbonate, and a variety of herbal products (including propolis extract, calendula flower extract, Echinacea flower extract, goldenseal extract, vitamins A, D, & E, tea tree oil, yellow beeswax, olive oil, benzoin tincture, and honey). The effectiveness of zinc for the treatment of cold sores was discussed previously, and the effect of the other products is not known. Further data are needed to determine the role of L-lysine in the treatment or prophylaxis of cold sores.
1. Godfrey HR, Godfrey NJ, Godfrey JC, et al. A randomized clinical trial on the treatment of oral herpes with topical zinc oxide/glycine. Altern Ther Health Med. 2001;7:49-56.
2. Singh BB, Udani J, Vinjamury SP, et al. Safety and effectiveness of an llysine, zinc , and herbal-based product on the treatment of facial and circu-moral herpes. Altern Med Rev. 2005;10:123-127.
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