Petroleum jelly is generally safe to use. But rarely, breathing in (inhaling) fat-based substances (lipoids) — such as petroleum jelly or mineral oil — for long periods can cause lung problems.

Petroleum jelly applied to the inside of the nostrils usually drains down the back of the nose with normal nasal secretions. Then it is swallowed. Rarely, small amounts of the jelly can travel into the windpipe (trachea) and lungs. Over many months, the jelly can build up in the lungs. This buildup can lead to potentially serious swelling and irritation (inflammation) in the lungs known as lipoid pneumonia.

In some people, lipoid pneumonia causes no signs or symptoms. In others, lipoid pneumonia may cause cough, chest pain or shortness of breath.

Lipoid pneumonia is often found on a chest X-ray or CT scan. Sometimes, a doctor confirms the diagnosis with a bronchoscopy.

When lipoid pneumonia is caused by petroleum jelly, then generally the only treatment is to stop the use of the jelly.

If you have concerns about the use of petroleum jelly, relieve nasal dryness by using a vaporizer or humidifier instead or try over-the-counter saline nasal spray. If you must use a lubricant, choose the water-soluble variety. Use it only sparingly and not within several hours of lying down.