According to Women's Health Queensland Wide, women can produce milk when they are not pregnant. Many things can cause milk production, such as certain medications and supplements, irritated nipples or disease.
The production of milk while not pregnant is called galactorrhea, according to Women's Health Queensland Wide. This milk production, or lactation, occurs for a multitude of reasons. Certain medications, such as antidepressants or blood pressure medications, stimulate milk production. Drugs also cause lactation, especially marijuana or opium-based drugs, as well as certain herbal supplements. Milk production can also occur as a side effect of birth control.
According to Women's Health Queensland Wide, milk production is more likely to occur as women get older and go through more pregnancies. At this point, squeezing, stimulating or irritating the nipples is enough to cause lactation or a milky discharge.
Women's Health Queensland Wide warns that inappropriate milk production can also have more serious underlying causes, such as thyroid or kidney disease. In this case, women need to be aware of other symptoms of the diseases, such as hormone imbalances that cause menstruation irregularity and acne. A problem with the pituitary gland, which produces hormones, especially those involved with pregnancy, can also cause galactorrhea.