My lip has swollen and i dont know why it has.

Lip swelling: Lip swelling can have many causes. The most immediately concerning would be as a symptom of severe allergic reaction or anaphylaxis. This can be accompanied by flushed red skin, itchy hives and nausea. Any time there is swelling in the area around the throat including the mouth, it is recommended to seek immediate care because of the risk for the swelling to block the airway and cause suffocation

Minor trauma: Even minor trauma can cause swelling of the lip. Put an ice pack on it. If you develop breathing problem, go to the nearest hospital. If both lips are swollen it may be allergy to some thing you may applied to your lips. Have a healthy diet, exercise 30 minutes/day, drink plenty of water, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/.