The Role of Vaginal pH in HIV Transmission Risk

The Role of Vaginal pH in HIV Transmission Risk

Many people are aware that the acidity and pH levels in the vagina have a great deal to do with maintaining good vaginal health.

Keeping the vaginal healthy and the pH levels at an even keel can be like walking a tightrope with the slightest change making a big difference.

Things like diet, medication, and the menstrual cycle are just a few of the things that can influence vaginal pH levels. What people may not know is that the pH level of the vagina can influence the risk of a woman contacting HIV.

In a healthy vagina, lactobacilli, which are the healthy organisms and bacteria found in a vagina, thrive and grow at a normal healthy rate. The lactobacilli’s main function in keeping a woman’s vagina healthy is to use the glycogen in the vagina as an energy source and break it down into lactic acid and glucose. This in turn helps keep the vagina’s pH balance at a healthy level. When the pH is at a healthy level, the vagina’s acidity is able to kill germs, and it helps provide a mucous membrane of squamous cells to cover and protect the cervical canal.

Healthy pH balance contributes to HIV transmission risk in a variety of ways. One way is helping to protect the vagina from microscopic cuts and abrasions that allow HIV to enter the body. These microscopic cuts and abrasions happen when the vagina is inflamed, usually due to infection, tampons, douching or trauma and can cause the pH balance to rise.

Vaginal infections such as Bacterial Vaginosis and sexually transmitted infections such as Chlamydia greatly influence the pH level of the vagina creating an unhealthy environment and a greater risk for HIV transmission. Further, sexually transmitted infection such as syphilis and herpes that cause any type of open sore that can occur in the vagina as well as the rest of the genitals also provides access to the body for HIV transmission.

The pH balance changes over the menstrual cycle which means there are times during the menstrual cycle where a woman is more susceptible to HIV transmission. During the last half of the menstrual cycle when a woman is fertile, the acidity in the vagina changes and the immune system is compromised so sperm is not destroyed and a woman’s chances for pregnancy are optimal. This also makes it easier for a woman to be infected with HIV. Further, when estrogen levels are lower during certain phases of the menstrual cycle, the vaginal mucous can become thin which makes it easier to get cuts and abrasions.

A sexual practice that influences healthy vaginal pH and increases HIV transmission is the use of vaginal drying agents. Vaginal drying agents can be anything from stones, toilet paper, leaves, powders and clothes that are inserted into the vagina to soak up normal vaginal lubrication. This is done in some cultures where dry sex is seen as more desirable than sex with vaginal lubrication. In these cultures vaginal lubrication during intercourse is an indicator of infidelity on the woman’s part, is seen as a curse or bad luck. Not only does the dryness in the vagina alter health pH level but the woman can experience lacerations and other trauma to the vagina that create yet another opening into the body for HIV to enter.

This all reinforces the need for women to keep their vagina’s healthy overall, but also to help protect themselves from HIV transmission.


Written by Mark Riegel, MD

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