Lip numbness may be caused by low blood calcium, exposure to cold temperatures, Raynaud’s disease, food allergies, toxic chemical exposure, Lyme disease, reactions to some medications or even cancer, according to HealthGrades. Additional causes of lip numbness include thyroid imbalances, Guillain-Barré syndrome, ischemia, hyperventilation, neuropathy or multiple sclerosis.
Some causes of lip numbness are harmless, such as the sensation patients feel after receiving a local anesthetic during a dental procedure, explains HealthGrades.
Underlying health conditions can cause damage to the nerve pathways between the brain and body, resulting in lip numbness and various other symptoms, including difficulty walking, impaired muscle coordination, loss of muscle strength and sporadic twitches and spasms in the muscles, according to HealthGrades.
Ingesting toxic chemicals can cause numbness in the lips and other areas of the body and constitutes a medical emergency, according to HealthGrades. If a person experiences changes to her speech patterns, has trouble swallowing, experiences swelling in the face and mouth or cannot breathe properly, it is imperative that emergency medical attention is sought immediately. Lip numbness should be analyzed by a doctor to find a cause and determine a proper plan of treatment. Doctors need to know of any accompanying symptoms, such as changes to bowel movements, tingling, redness, bleeding, nausea and loss of bladder control. All of these signs are helpful to doctors when diagnosing the origin of lip numbness.