According to Care2, Vaseline should be used as a lubricant on the external areas of a person's body only. When used inside the body, it can foster bacterial growth and/or cause internal irritation.
During intimacy, Vaseline can corrode condoms, making them ineffective for preventing disease and pregnancy. Petroleum jellies, like Vaseline, may contain impurities that can cause cancer. The petroleum can negatively impact liver function if used internally. Vaseline can lubricate dry skin, such as elbows, knees and feet in the winter time. It can also be used to lubricate and soften facial skin to more easily pluck eyebrows and remove gunk from false eyelashes.