What could cause a big bump on my lip to appear out of nowhere?

Cysts (fluid filled sacs) are common throughout the body including along the lip line. They are typically slow growing and their size may fluctuate over time. However, if cysts become infected, they can grow rapidly and typically are associated with redness and discomfort. Other infections - including viral and bacterial infections - can cause relatively rapid swelling near the lips. Swelling of all or part of the lips themselves could be related to angioedema. This is a medical emergency. Angioedema is a type of swelling that can affect the deeper layers of the skin and is often caused by allergic reactions or side effects from medicines. For example, some blood pressure medicines, like ACE inhibitors (eg. lisinopril, benazepril) are associated with sudden swelling of the lips or tongue. Angioedema can also be related to hereditary angioedema, a rare and genetic condition that leads to episodes of swelling without a clear trigger. If you develop rapid lip swelling, particularly if associated with trouble breathing or hives, you should use our free symptom checker or be evaluated by a healthcare professional immediately.