What to do if my lip swelling so sudden?

Need clarification: Could be a few different causes of lip swelling. For example herpes simplex (cold sore) causes lip to enlarge and swell, but it is usually accompanied with pain and tingling. If you had a trauma (were hit eg.) on the mouth it would likely swell. And if you had recent dental work your lips could possible swell. Also allergies can cause lip swelling as can inflammation, infection near lip. See dr.