Hello there! Did you suffer an injury to your lip? If not, then this kind of swelling in many cases is associated to allergic reaction to certain foods or medicines. Consult a dental surgeon for diagnosis. You may also need second opinion from a dermatologist or allergy specialist after that. Hope this helps. Take care!
Disclaimer : The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding your medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.