Microbicides 2006: High concentrations of lime juice kill HIV but too caustic to use as a microbicide

Using high concentrations of lime juice as a vaginal douche to prevent HIV or other sexually transmitted infections (STIs) can cause severe abrasions to the vaginal epithelium, and would probably only increase the risk of HIV transmission, according to a safety study presented at the Microbicides 2006 conference this week in Cape Town, South Africa. Although another study suggested that using lower concentrations (up to 20%) may be safer, laboratory studies have found such concentrations are too low to kill HIV.

Vaginal douching

Douching the vagina (with soap and water, or other liquids such as vinegar, diluted lemon or lime juice — even soft drinks) is a common cultural practice in Africa, particularly after sex. According to one study in Mozambique “both women and men believe that vaginal cleansing should occur routinely after sex to remove impurities and prevent diseases.” A survey of 266 women and 174 men in Zimbabwe indicated that 97.4% of the women washed the inside of the vagina and that 140 (80.5%) men assented to the practice

Previous studies have documented that sex workers in Nigeria commonly use high concentrations (50% or 100%) of lime juice intravaginally to prevent either HIV or STIs or pregnancy — even though this is essentially just a folk remedy.

Preclinical studies

A laboratory study of lime juice presented at the conference found that it does indeed kill HIV. At a 10% concentration, lime juice can inactivate HIV within five minutes. But in the presence of semen, it takes a 50% concentration at least 30 minutes to kill all the virus — shorter time periods or lower concentrations fail to demonstrate significant inactivation.

But the study also found some suggestions that lime juice might damage mucosal tissues — particularly if the tissue was already irritated. A second preclinical study, which also looked at lemon juice, found that both juices were markedly toxic to a variety of human cells, and concluded that while the juice might kill HIV in the cultures, it killed everything in the culture.

Nevertheless, women do it — and, if effective, the potential benefits would be great.

“Limes are easily accessible, they’re inexpensive and if lime juice were to be proven safe and effective, it would be wonderful and an answer to many people’s prayers,” said Dr. Christine Mauck, who presented one of the safety studies.

Safety studies

Two studies set out to determine the safety of douching with lime juice using different concentrations. One, conducted by Dr Anke Hemmerling,of the University of California, Berkeley, concluded that the practice was relatively safe — at lower concentrations.

In her trial, twenty-five women were randomly assigned to apply a tampon soaked either without juice or with a 10% or 20% concentration of lime juice for 14 consecutive days. Tests for genital infections, measurement for signs of inflammation and a colposcopy were performed before and after treatment.

None of the participants showed signs of severe vaginal irritation, although more than 70% of women in all groups reported minor and temporary side effects such as dryness. No other significant problems were observed. However, in light of the preclinical activity studies, these concentrations would be unlikely to affect HIV transmission.

Dr. Mauck’s study compared three concentrations of lime juice (25%, 50% and 100%) to plain water in 47 abstinent women who applied 24 ml of their assigned fluid twice daily for 6 consecutive days in 2 consecutive menstrual cycles, using either a douche or a fluid-saturated modified tampon in each cycle. Vaginal health was evaluated by colposcopy and cervicovaginal lavages (CVLs) at baseline, one hour after the first application (colposcopy only) and on days 3 and 7.

All study arms experienced some genital irritation — even with water. But at the two higher concentrations of lime juice, there were deep abrasions to the women’s vaginal epithelium. At the highest dose, more than 65% had genital irritation, 50% experienced deep epithelial abrasions and more than 70% reported experiencing pain.

According to Dr. Mauck, high concentrations of lime juice are even more harmful than nonoxynol-9, which despite being used as a microbicide for years, was shown to so irritate the mucosa that it actually increased HIV transmission.

“There’s a very small level of safety and a low therapeutic index — that’s the biggest problem with lime juice. While lime juice is inexpensive and available, this does not justify holding it to a lower standard of safety and efficacy than a microbicide being developed as a drug. To do so would be unfair to the women who so desperately need and deserve a safe and effective prevention method, Dr. Mauck concluded.”