A natural lubricant is either a biological or man-made liquid that is designed to reduce friction and pain during sexual intercourse. Both men and women naturally secrete lubrication in their genital regions during sexual arousal, and from a scientific standpoint these are the only true “natural” lubricants. Some commercial products will also use this name if they are made with natural rather than synthetic ingredients, however. Many pharmacies and health supply stores sell gel or water-based lubricants that people can use during intercourse to increase or add to the fluids their bodies are creating naturally.
Production in Men
Men who are sexually aroused often leak a small amount of clear fluid from the tip of their penis, often called pre-ejaculate or "pre-cum." It does not usually contain any semen. Pre-cum is produced in the Cowper's gland before ejaculation, and serves the dual purpose of protecting the sperm from the acid inside the vagina and cutting down on friction during penetration. Friction is often somewhat uncomfortable for both parties, and can also make it harder for the sperm to travel in search of an egg to fertilize.
Female Secretions
The process is similar in women. During arousal, the walls of a woman's vagina become filled with blood. The pressure of the blood forces plasma through the vaginal tissues, and a woman's genitalia become "wet” as a result; this wetness makes the opening slick, facilitating penetration. The Bartholin's glands, located beneath the opening of the vagina, will also produce mucus to augment the plasma. Sperm ejaculated into this environment often have an easier time navigating to the egg than they would if conditions were drier.
Outside of Intercourse
Lubricants are sometimes secreted outside of sexual situations, too. Boys and young men going through puberty often experience somewhat random dripping from their penis as the organ develops and gets ready for its reproductive prime. Women may also find that their genitals become wet and lubricated at different points in their menstrual cycles, usually as a result of hormonal shifts.
Commercial Products
Biologically produced natural lubricant isn’t always enough for intercourse to be comfortable for both partners, particularly if barriers like condoms or spermicides are used. A lot of different factors can impact how much lubrication men and women produce, but different medications, stress, and even environmental things like temperature can all play a role. People who are concerned about friction or pain during sex often look for man-made lubricants, also known as "personal lubricants" or simply "lube." When these are made with only natural ingredients, they are sometimes sold with the “natural” label attached.
Most commercial lubes in this category are water-based and get their slipperiness from vegetable or plant oil. Shea butter, aloe, and green tea are also common additives. These products are sometimes marketed as an alternative to more conventional, chemically-derived lubricants, especially for people with allergies to synthetic ingredients or concerns about the environmental effects of chemical production.
Different brands often have different standards when it comes to what “natural” means, and as a result anyone who is concerned about how a product is made or exactly what it contains should usually read the labeling very carefully. Just because something is natural doesn’t always mean that it is the best choice. Some ingredients can cause latex to break down or disintegrate, for instance, which can be a big problem for couples using condoms, and more obscure oils can cause reactions and rashes, particularly on skin that is irritated or broken.
Common Concerns
It’s usually considered somewhat normal for peoples’ biological lubricant to fluctuate a little bit, with some days where there is more than others. Anyone who is concerned that they don’t have enough — or, in the alternative, that they are producing too much — is usually best served talking to a healthcare provider. Sometimes simple things like dehydration or prescription drug side effects are to blame, but chronically low or high lubrication can also be a sign of a more serious condition like a hormonal imbalance or a glandular issue.