Vaginal lubrication

Overview
Vaginal lubrication is the naturally produced lubricating fluid that reduces friction during sexual intercourse. It is often produced on occasions of women's sexual arousal. Vaginal dryness is the condition in which this lubrication is insufficient.

Composition
The lubrication fluid contains water, pyridine, squalene, urea, acetic acid, lactic acid, complex alcohols and glycols, ketones, and aldehydes. The fluid is typically clear and more resembling of male pre-ejaculate than male ejaculate. It can vary in consistency, texture, color, and odor, depending on sexual arousal, the time of the menstrual cycle, the presence of an infection, and diet.

Vaginal fluid is slightly acidic and can become more acidic with certain sexually transmitted diseases. The normal pH of vaginal fluid is between 3.8 and 4.5, whereas male semen is typically between 7.2 and 8.0 (a neutral substance has a pH of 7.0).

Changes in vaginal lubrication
Certain medications, including some over-the-counter antihistamines, as well as life events such as pregnancy, lactation, menopause, aging or diseases such as diabetes, will inhibit lubrication. Medicines with anticholinergic or sympathomimetic effects will dry out the "mucosal" or wet tissues of the vagina. Such medicines include many common drugs for allergic, cardiovascular, psychiatric, and other medical conditions.

Role in disease transmission
Safe sex educators warn that the vaginal fluids of a woman who is infected with HIV or other STIs can transmit the disease, even in the absence of direct penile-vaginal sexual intercourse, so direct contact is discouraged.

Artificial lubrication
When natural lubrication is insufficient, penetrative intercourse may be uncomfortable or painful. A personal lubricant applied to the vaginal opening and/or the penis can prevent this discomfort. More rarely, a vaginal suppository may be inserted prior to intercourse.

Oil-based lubricants can weaken latex and reduce the effectiveness of condoms, latex gloves, or dental dams as either forms of birth control or for protection from sexually transmitted diseases, so water- or silicone-based lubricants are often used instead.