What Is Causing My Upper Lip Numbness?

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.