Lip swelling due to a mild allergic reaction may last up to approximately four days with or without medication, according to the University of Maryland Medical Center. Swelling of the lips that results from dental implants can last up to five days after the procedure, says Dr. Richard Mitchell of Dental-Health-Advice.
Swollen lips may also be caused by an outbreak of hives, which can occur at various locations on the body due to allergies, stress, insect bites or infections. Swelling due to hives may last from several hours to several months, depending on the severity of the condition, notes the University of Texas at Austin's Health Services website.
People who have certain serious infections, such as the herpes simplex virus, may develop lip sores and swelling when they are experiencing an outbreak of the ongoing condition, explains Johns Hopkins Medicine's Health Library. During an outbreak, swollen or blistered areas of the skin begin to scab over in about six days and the outbreak usually subsides altogether within approximately 10 days.
The amount of time a swollen lip lasts varies depending on the reason the lip is swollen and what treatment is used to heal it. A severe allergic reaction, for example, may take longer to heal than a mild one and may also require the use of anti-inflammatory steroid medications prescribed by a doctor, reports the University of Maryland Medial Center.